Telecom/1996-04-telecom-walnutcreek.iso/miscellaneous/telecom.newsgroup.faq

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From: [e-mail] (Dave Leibold)
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Subject: TELECOM Digest - Frequently Asked Questions (v7)
Status: RO

TELECOM Digest - Frequently Asked Questions - v.7           17 December 1995

* Frequency of Updates: approximately annual (special updates are possible)

* FAQ contributions to: [e-mail]
                        or, [e-mail]
                        or, [e-mail]

Introduction...

This is a list of frequently asked questions made in the TELECOM Digest.
New versions of the list are occasionally made available to deal with new,
corrected or updated questions. Many contributors have made the FAQ what
it is today (those listed in the "Who contributed to this FAQ?" question
are hereby thanked).

Check the Archives...

Much of the telecom information that is requested can be found in the
TELECOM Digest Archives, which is a collection of text files on telecom
topics. These archives are available for access through the FTP protocol at
massis.lcs.mit.edu. Other archive sites may be available besides the ones
mentioned here, plus various FTP mail and WWW servers. The monthly posting
of the description of TELECOM Digest should contain specific details on how
to access the Archives.

This list is in the Archives under the file name:

         frequently.asked.questions

The index to the Archives should be obtained and kept for reference.
This index has also occasionally appeared as a posting in the Digest.
You should also read the Archives file intro.to.archives to get a
better understanding of how the Archives operate.

A list of terms commonly used in TELECOM Digest may be obtained from
the Archives under the file names glossary.acronyms, glossary.txt and
glossary.phrack.acronyms.

Try direct inquiries...

Direct netmail requests to persons posting on topics of interest to you may
also be helpful. In fact, doing things "behind the scenes" can be more
productive as the Digest Moderator is frequently swamped with other items.
Future editions of this list could include netmail addresses of contacts for
certain topics (say for ISDN, cellular, area codes/numbering plan, consumer
protection matters, etc.); offers to that end would be appreciated.

Where to contact the FAQ maintainer...

Suggestions for other common questions, or corrections or other amendments
to this file may be made to [e-mail] (Fido
1:259/730) or [e-mail] or [e-mail]. Note that any or
all of these addresses are subject to change.

This file is updated at least annually; special updates may be made as
time and circumstances permit.

Disclaimer Type Stuff...

All information herein should be considered subject to correction or
change. No endorsements or promotions of specific products or companies
are intended. Any specific references are made for example only, or in
order to adequately deal with certain subjects.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

List of subjects and questions covered as they appear in this list:

Technical

 - How do phones work?
 - What is a Central Office? What is a switch? What roles do Central
   Offices and switches play in the telephone network?
 - How many different types of switches are there, how do they differ,
   and what switches are most commonly found in use?
 - When did the first ESS (electronic) switch go into service?
 - What frequencies do touch tones use for which numbers?
 - What are the A, B, C and D touch tone keys used for? Why are they
   not found on touch tone phone sets?
 - The # key - what is it officially called? How many different names are
   there for it? Why is it sometimes called a "pound" key?
 - What is call supervision?
 - How can I find out what my own phone number is?
 - Are there other kinds of test numbers used?
 - Can a US modem or phone work in the UK, or some other European
   country? (Or vice versa, or in general for international substitution
   of phone equipment)
 - What do "tip" and "ring" mean?
 - Why use a negative charge (-48 volts) for Ring instead of a positive
   charge (such as +48 volts)?
 - What is "Caller ID" (or Call Display, or CNID (Caller Number
   Identification))?
 - How can I get specifications on how Caller ID service works?
 - What is the best way to busy a phone line?  I have a bank of modems
   which are set up as a hunt group. When a modem dies I would like to
   be able to busy out the line that is disconnected, so that one of the
   other modems in the hunt group will take the call.
 - What telephone wiring should be used?
 - What is the difference between Caller ID/CNID and ANI?
 - What is Switched 56?
 - How does caller number delivery work on 800 (or 900) service?
 - Is there some way I can use a modem to send text messages to my
   alphanumeric pager?
 - How can I prevent an extension from interfering with a modem call?

Numbering

 - What is a numbering plan?
 - Who has authority over numbering plans?
 - How was the country code system developed?
 - What is the correct way to write a telephone number for
   international use?
 - What are the access codes used in international dialing?
 - What does NPA, NNX, or NXX mean?
 - What happens when all the telephone numbers run out in a given area?
 - How long can a phone number be (internationally speaking)?
 - What is Time T?
 - What is an overlay area code?
 - How was extra numbering capacity achieved in North America?
 - In North America, why did long distance dialing within area codes
   change so that 1 + home area code + number has to be dialed, or
   change to just seven digits (like a local call)?
 - What is an "interchangeable" area code?
 - Why were "interchangeable" area codes introduced?
 - Why not increase the number of digits in the North American
   Numbering Plan?
 - How will we make room if North American area codes are running out?
 - What "interchangeable" area codes been assigned?
 - What about expanding area/STD codes in other countries?
 - How are area codes assigned?
 - What is Bellcore?
 - How can I contact Bellcore?
 - How can I get exchange/billing data? What is a V&H tape?

Regulatory & Tariffs

 - How are long distance call costs rated?
 - What's this about the FCC starting a modem tax for those using
   modems on phone lines?
 - Why is a touch tone line more expensive than a rotary dial line
   (in many places)?
 - How come I got charged at a hotel for a call where no one answered?
   Why is the timing on some of the long distance carriers inaccurate?
 - What is AT&T Tariff 12?
 - What are the ITU and CCITT?

Competition

 - Which countries have competitive telecommunications services?
 - What is a COCOT?
 - What is an AOS?
 - What is "splashing"?
 - Where can I find a list of equal access (10XXX) codes?
 - How can I tell who my default carrier is (or which carrier belongs
   to a 10XXX+ code)?
 - What is a LATA?
 - Where can LATA maps be found?

Features

 - What is the calling card "boing" and what is it made of?
 - What are codes like *70?
 - How can one dial *70 on a non-touch-tone (pulse/rotary) phone?
 - How can I prevent the call waiting tone from beeping in mid-conversation?
 - What is distinctive ringing?

Miscellaneous

 - Is there a way to find someone given just a phone number?
 - Who are the Telephone Pioneers?
 - Where can a Cellular/Mobile Radio mailing list be contacted?
 - How are VCR+ codes generated?
 - What is CLLI?
 - Why do movies often use 555-xxxx numbers?
 - Are there cases of local calls across international borders?
 - Which countries have freephone or "800" services?
 - How can one call 800 numbers from other countries?
 - Which World-Wide Web (WWW) sites have telecom information?
 - What's an ObTelecom?
 - Who contributed to this FAQ?

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

---------
Technical
---------

Q: How do phones work?

A: A file in the TELECOM Digest archives under the name "how.phones.work"
   is available and should explain some details of the workings of
   the common telephone.

Q: What is a Central Office? What is a switch? What roles do Central
   Offices and switches play in the telephone network?

A: A Central Office (CO) is the facility to which the telephones in
   a public telephone network are connected. It is the front line in
   terms of the whole telephone system; dial tone, telephone ringing,
   connection to other telephones, or outside trunks, is done here.

   A "switch" is a general term referring to facilities where
   telephone traffic is routed from one destination to another.
   The Central Office has a switch in a local sense; calls within
   a municipality can often be completed within a single switch.
   Beyond this, there are switches for long distance or regional
   traffic, many of which are not directly connected to user
   telephones.

   A hierarchy of switching centres was developed in North America.
   Level 5 switches are the most common and are generally the
   local Central Office switches. Level 4 switches are used in
   regional or larger local settings and occasionally are connected
   to customer telephones. Level 3, 2 and 1 switches serve larger
   regions in turn. In general, a call that cannot be handled at
   one level of switching (by reason of distance covered, or congestion
   at a given switch) is passed onto the next higher level until the
   connection is completed. The breakup of AT&T in the USA and the
   introduction of new services will no doubt have disrupted this
   hierarchy, but this illustrates how a call can progress from one
   place to another.

   A large city usually has many central offices, each serving a
   certain geographical area. These central offices are connected
   to other central offices for local calling, or to higher level
   switches, or into long distance networks.

Q: How many different types of switches are there, how do they differ,
   and what switches are most commonly found in use?

A: The original telephone switches were manual, operator-run switchboards.
   Today, these are generally found in developing countries or in certain
   remote locations as newer types of switches allow for connection to
   automatic telephone service.

   Step-by-step was the first widely-used automatic switching method. This
   was an electro-mechanical system which made use of rotating blades and
   mechanical selection of various levels. Dial pulses would be used to cause
   the switches to select switch groups until the whole number was dialed.
   Some step-by-step facilities still exist today, but will eventually be
   replaced by more modern forms of switching (typically a digital facility).
   Step-by-step, with its mechanical nature, can be difficult to troubleshoot
   and maintain, and does not inherently support touch tones or special
   calling features without special addition of equipment.

   Step-by-step's "progressive control" could not be rerouted to avoid points
   of congestion in the switches but was rather at the mercy of which numbers
   would be dialed by the telephone users. There was also no capability to
   select a variety of routes for the call. Different technologies were
   developed to solve the inflexible routing problem, among other things.

   Systems were developed where a "sender" could accept a dialed number,
   then interact with a distant switch to establish an appropriate route
   for the call to be completed. The concept of "common control" was
   introduced: progressive customer dialing control would be replaced
   by giving the central office the ability to determine the call's route.

   The first common-control switches were developed by Western Electric
   ("Panel Type") and IT&T ("Rotary"). Panel Type switches used wipers
   that moved vertically through contacts. Rotary equipment used wipers
   that moved through contacts arranged in a circle. The two switches
   were conceptually similar, to the point that switches of both types
   could be directly connected. Most large U.S. cities used such switches.
   Rotary switches were particularly popular in Paris, France, among
   other places.

   Crossbar was the next step in electro-mechanical switching. Rather than
   the types of switches used in step-by-step or in Panel/Rotary, connections
   were completed by means of a matrix of connectors, arranged in a grid.
   The configuration of crossbar matrix elements was under "common control"
   for routing calls.

   Electronic switches (e.g. ESS) were developed in the 1960's. These were
   often reed relay switches with an electronic common control faster than
   previous crossbar systems. The fewer moving parts there were, the better.
   Services such as call waiting or call forwarding would eventually be
   possible under electronic systems.

   Finally, the new digital electronic systems provide for a fully-
   programmable telephone operation. These are all-electronic systems
   which would process calls without moving parts (i.e. solid-state
   switching) and full computerisation of control. Voice traffic would
   now be converted to digital format for use with digital transmission
   facilities. A wide variety of user services can be implemented such
   as sophisticated types of call forwarding or Caller ID or ISDN
   (Integrated Services Digital Network). Ultimately, all telephone
   subscribers will be served by such switches as these.

   Presently, various kinds of switching systems are in use, and the
   proportions of what technologies are in use in given regions will vary.
   The most common will eventually be the digital electronic systems.
   There are significant costs associated with upgrading the network to
   digital, fully-programmable switching, but the eventual goal of phone
   companies worldwide is to modernise Central Offices and long distance
   networks to such switches. In the meantime, the various switching
   technologies in use must provide compatibility with each other in
   terms of signalling among switches, call routing capabilities, and
   the ability to use existing types of phone equipment.

Q: When did the first ESS (electronic) switch go into service?

A: In the U.S., the first 1ESS switch went into service May 1965 in
   Succasunna, New Jersey. This was a software-controlled switch using
   magnetic reed relays.

   In Canada, the first ESS was set up in Montreal, circa 1967.

   While there were substantial capabilities with such ESS switches as
   1ESS or SP-1, these are being replaced by modern digital switches
   (e.g. Northern Telecom DMS, Ericsson AXE).

   Any information regarding international firsts in electronic or
   digital switching would be welcome as a future enhancement to the FAQ.

Q: What frequencies do touch tones use for which numbers?

A: The touch tone system uses pairs of tones to represent the various keys.
   There is a "low tone" and a "high tone" associated with each button
   (0 through 9, plus * (star) and # (the thing that's called various names:
   octothorp(e), hash, number sign, "pound" symbol). The low tones vary
   according to what horizontal row the tone button is in, while the high
   tones correspond to the vertical column of the tone button.

   The tones and assignments are as follows:

          1     2     3     A  :  697 Hz

          4     5     6     B  :  770 Hz
                                           (low tones)
          7     8     9     C  :  852 Hz

          *     0     #     D  :  941 Hz
        ----  ----  ----  ----
        1209  1336  1477  1633 Hz
               (high tones)

   When the 4 button is pressed, the 770 Hz and 1209 Hz tones are sent
   together. The telephone central office will then decode the number
   from this pair of tones.

   The tone frequencies were designed to avoid harmonics and other problems
   that could arise when two tones are sent and received. Accurate
   transmission from the phone and accurate decoding on the telephone
   company end are important. They may sound rather musical when dialed
   (and representations of many popular tunes are possible), but they are
   not intended to be so.

   The tones should all be +/- 1.5% of the specified frequency. The high
   frequency tone should be at least as loud, and preferably louder than
   the low frequency. It may be as much as 4 dB louder. This factor is
   referred to as "twist."  If a Touchtone signal has +3db of twist, then
   the high frequency is 3 dB louder than the low frequency. Negative
   twist occurs when the low frequency is louder.

Q: What are the A, B, C and D touch tone keys used for?
   Why are they not found on most touch tone phone sets?

A: These are extensions to the standard touch-tones (0-9, *, #) which
   originated with the U.S. military's Autovon phone network. The original
   names of these keys were FO (Flash Override), F (Flash), I (Immediate),
   and P (Priority). The various priority levels established calls with
   varying degrees of immediacy, terminating other conversations on the
   network if necessary. FO was the greatest priority, normally reserved for
   the President or very high ranking officials. P had a lesser priority,
   but still took precedence over calls that were placed without any
   priority established.

   Today, the tones are commonly referred to as the A, B, C and D tones
   respectively; each of these tones use 1633 Hz as their high tone. These
   are found mainly used in special applications such as amateur radio
   repeaters for their signalling and control. Modems and touch tone circuits
   tend to include the A, B, C and D tones as well. These tones have not been
   used for general public service, and it would take years before these
   tones could be used in such things as customer information lines; such
   services would have to be compatible with the existing 12-button touch
   tone sets in any case.

Q: The # key - what is it officially called? How many different names are
   there for it? Why is it sometimes called a "pound" key?

A: That key usually found under the 7 and to the right of 0 gets to be
   called cross-hash, cross-hatch, enter, hash, noughts-and-crosses,
   number-sign, octothorp(e), pound, pound-sign and no doubt other
   names. There is some officiality to the term "octothorp(e)", spelled
   with or without the 'e' depending on location or who you hear.

   The term "number-sign" seems to be in common use for interactive voice
   response systems, sometimes with an explanation that this button is
   to the right of the 0.

   As for the term "pound key", this might have something to do with the
   # (number sign) in data being replaced by the UK Pound symbol in some
   setups.

   This topic was discussed in 1988 on the TELECOM Digest (Vol. 8, #190
   with plenty of follow-up discussion) which should be available in
   the FTP Archives.

Q: What is call supervision?

A: Call supervision refers to the process by which it is determined that
   the called party has indeed answered. Long distance calls and payphone
   calls are normally charged from the time the called party answers, and
   no charges should be assessed where the other end doesn't answer nor
   where the called party is busy or blocked by network problems.

Q: How can I find out what my own phone number is?

A: If the operator won't read your number back to you, and if you can't
   phone someone with a Calling # ID box, there are special numbers
   available that "speaks" your number back to you when dialed. These
   numbers are quite different from one jurisdiction to the next. Some
   areas use 200 222.2222; others just require 958; still others 311 or
   711 and others have a normally-formatted telephone number which can
   be changed on occasion (such as 997.xxxx).

   Such numbers exist in many countries; 175 is one number in the UK
   while 19123 is one in Australia. There is no general rule for the
   format of such numbers. These are normally assigned to codes outside
   normal customer number sequences, however.

   In areas where Caller ID is available, one could arrange to call
   someone with an activated display unit and have that called party
   read back the caller's number.

Q: Are there other kinds of test numbers used?

A: Yes. Again, space (and available information) does not permit a complete
   list of what each telephone company is up to in terms of test numbers.
   The most common number is a "ringback" or self-ring test number. When a
   two or three digit number is followed by all or the last part of your
   phone number, another dial tone occurs. Tests for dialing or ringing may
   then be done. The ringback methods in some jurisdictions will vary.

   Other numbers include intercom circuits for telephone company staff, or
   switching centre supervisors, or other interesting tests for call
   supervision or payphone coin tests.

   One famous kind of test number belongs to NYNEX, the regional Bell
   telephone company operating in the northeast U.S.A.. In New York at
   least, there are "9901" numbers, or local numbers of the form xxx.9901,
   which result in a recording which identifies the exchange represented
   by the first three digits. The 9901 numbers may not necessarily exist
   for all combinations of first three local number (central office code)
   digits.

   All these tests and services vary with each phone company; they are
   not usually found in the phone book, needless to say.

Q: Can a US modem or phone work in the UK, or some other European
   country? (Or vice versa, or in general for international substitution
   of phone equipment)

A: Often it can, provided that the AC Voltage and the physical jack
   are compatible or converted, and it can generate pulse dialing,
   as many exchanges are not equipped for touch tone.

   However, in most European countries it is illegal to fit non-approved
   equipment. In the UK, approving equipment is the responsibility of BABT,
   and the penalty is confiscation of the equipment plus a fine of up
   to 2000 pounds sterling. Approved equipment has a mark, usually a
   sticker, of a green circle with the words "APPROVED for connection
   to the telecommunication system specified in the instructions subject
   to the condition set out in them" and the number of the BABT
   certificate. Non-approved items, if they are sold in the UK, must
   have a sticker with a red triangle with similar wording except that
   it's saying the exact opposite. It's perfectly legal to sell
   non-approved equipment subject to the above, as there may be a
   valid reason for using it, just not on the UK network.

   In Canada, telephone equipment requires approval from the government
   department known as Industry and Science Canada, or formerly through
   the Department of Communications. Most equipment designed for American
   conditions should be acceptable in Canada, and vice versa. A small
   sticker indicating Canadian government approval is normally found
   on approved devices.

Q: What do "tip" and "ring" mean?

A: The conductors of a wire pair to a telephone set are referred to as
   tip (T) and ring (R). Tip (T) is usually positive charge with respect
   to the Ring (R). Ring is typically at -48 volts (subject to voltage
   losses). Tip (T) is then at ground when no current is flowing.

   The actual voltages may differ in PBX/Key system situations (where 24
   volt systems can be found) or higher voltages can be used for situations
   where there are long distances among the subscribers and the switching
   offices.

   Two wires normally suffice to complete a connection between a telephone
   and the central office; any extra wiring would be for purposes such as
   as grounding, party line ringing or party line billing identification,
   or even for dial light power on phones such as the Princess.

   The Tip and Ring terms come from the parts of the plugs that were
   used for manual switchboards.

   In a U.S./Canada phone line, Tip is usually the green wire while Ring
   is red. Black wire is Tip and yellow wire is Ring if a second line is
   made from a four-wire cable. Colours and wiring rules will differ
   according to country and according to what sort of wiring is being
   done (punch-blocks, modular jacks, etc).

Q: Why use a negative charge (-48 volts) for Ring instead of a positive
   charge (such as +48 volts)?

A: The reason for doing this is galvanic corrosion protection. A conductor
   with a negative charge will repel chlorine ions, as Cl (chlorine) ions
   are negative also. If the line were to have a positive charge, Cl ions
   would be attracted.

   This form of corrosion protection is called cathodic protection. It
   is often used for pipelines, bridges, etc. Such protection was very
   important in the days of open wire transmission lines.

Q: What is "Caller ID" (or Call Display, or CNID (Caller Number
   Identification))?

A: This is a telephone company service that transmits the number of the
   party to your telephone during the ringing. A data receiver detects
   this signal and displays or otherwise accepts the number transmitted.

   Whether or not a number is transmitted depends on political limitations
   (some jurisdictions do not allow for Caller ID, or at least a fully
   operational version of it) and technical limitations (e.g. calls placed
   from older technology switches may not be identifiable; long distance
   services may not be set up to provide end-to-end ID yet).

Q: How can I get specifications on how Caller ID service works?

A: The official documentation on how the Caller ID or calling line ID
   works is available for purchase from Bellcore. A description of
   what those documents are and how to get them is available in the
   TELECOM Digest Archives file caller-id-specs.bellcore, or see the
   question "How can I contact Bellcore?" elsewhere in the FAQ. Local
   telephone companies may be able to provide technical information for
   the purpose of providing equipment vendors with specifications. Check
   the Archives for any other relevant files that may appear such as
   descriptions of the standards and issues surrounding services such as
   Caller ID.

   In Canada, for information about the service (known there as Call
   Display) contact: Stentor Resource Centre Inc, Director - Switched
   Network Services, 160 Elgin Street, Room 790, Ottawa, Ontario, K2P 2C4.
   (This address is changed from the one listed in FAQ #3 of 1992; note
   that the title may be subject to change as well). Tel: [phone]
   (or 781.3655) or toll-free within Canada: 1 800 265.6608. The relevant
   document is called "Call Management Service (CMS) Terminal-to-Network
   Interface", Interface Disclosure ID - 0001, November 1989 (or likely
   a newer version). The document used to be free, at least within Canada;
   in recent months, a CAD$50 charge was set by Stentor (the Canadian
   consortium of major telephone companies) for this information. This
   document deals with Bell Canada's Call Display standards, and may not
   necessarily be fully applicable outside their service area (provinces
   of Ontario and Quebec, parts of the Northwest Territories).

   An electronic Caller ID construction project was part of the February
   1994 edition of Electronics Now magazine (formerly Radio-Electronics).

   In general, the North American Caller ID information is passed to the
   telephone set in ASCII using a 1200 baud modem signal (FSK) sent between
   the first and second rings.

   In other nations where a Caller ID service exists, or is being
   established, contact the appropriate telephone company for information.

Q: What is the best way to busy a phone line?  I have a bank of modems
   which are set up as a hunt group. When a modem dies I would like to
   be able to busy out the line that is disconnected, so that one of the
   other modems in the hunt group will take the call.

A: "Our modem lines all enter on RJ21 "punchblocks" so I've got some
   rather nice clips that can be pushed over the terminals on the blocks
   and make contact with the pair that I want to busy out. Between the
   two terminals on the clip I have a red LED and a 270 ohm 1/2w resistor
   in series. As long as I get the clip on the right way, it busies out
   the line and lights up so I can see that I've got one of the lines
   busied out."

   "Since most of our modems have error correction, I've even gotten away
   with putting one of these on a line that's in use -- when the user
   disconnects, the line remains busy and I can then pull the modem at my
   leisure. The modem's error correction fixes the blast of noise from
   the clip as I slip it in."

   - Brian

[Further notes [from Dan Boehlke]:  A setup like this is not necessary.
For most systems simply shorting tip and ring together will busy out
the phone line. Some older systems, and lines that do not have much
wire between the switch and the point at which it terminates will need
a 270 ohm 1/2 watt resistor. The resistor is necessary because on a
short line will not have enough resistance to make up for the lack
of a load. Most modern systems have a current limiter that will prevent
problems. Older system may not have a current limiter and may supply
more current than modern systems do. In the followup discussion, we
learned that we should not do this to incoming WATS lines and other
lines that will cause the phone company's diagnostics centers to get
excited. A particular example was an incoming 800 number that was not
needed for a few days. The new 800 number was subscribed to one of
those plans that let you move it to another location in the event of
a problem. Well the AT&T diagnostic center saw the busy'ed out line as
a problem and promptly called the owner. -dan]

Q: What telephone wiring should be used?

A: This can be an FAQ file in itself. This will depend on the particular
   nation as do-it-yourself wiring may not be legal in many cases, or may
   require government-approved materials.

   One aspect is the use of "Twisted pair", a cable where two wires twisted
   about each other. This type of wiring has the advantage of reducing
   "crosstalk" and other interference problems from external electrical or
   magnetic sources. Twisted pair would be a better choice than straight,
   untwisted "quad" wiring and also make possible modulation schemes that
   allow for video transmissionn via phone lines (e.g. the ADSL standard).

Q: What is the difference between Caller ID/CNID and ANI?

A: Caller ID or CNID or Call Display refers to a service offered to
   telephone customers that allows for display or identification of
   telephone numbers from which incoming calls are made. ANI, or
   Automatic Number Identification, refers to operations within the
   telephone network that allow for the registering of a long distance
   caller's number for billing purposes and not a public offering
   as such.

   Special services such as incoming number identification for
   toll-free or premium program lines (800 or 900 service in
   North America) make use of ANI information and pass this
   along to the called party.

Q: What is Switched 56?

A: This is a data circuit operating at 56 kb/s that is "switched", or set
   up to allow the customer to dial up other Switched 56 lines.

   An "unswitched" connection (or "dedicated" or "leased") might be a direct
   link between company offices, but not directly accessible from other
   points in the general telephone network.

   Since much of the regular voice telephone network uses a digital data
   stream, Switched 56 delivers a data connection to the customer from the
   telephone company's switch rather than an audio connection. A Switched 56
   connection is useful for data and limited videoconferencing applications,
   since it carries data faster than even the v.34 modem standard.

   ISDN does the same job as Switched 56, plus other features. Switched 56
   may be available where ISDN isn't, however. Each location using Switched
   56 will require special units.

   The BYTE Magazine of November 1993 contains an article comparing
   Switched 56 with other forms of phone service.

Q: How does caller number delivery work on 800 (or 900) service?

A: The ANI (Automatic Number Identification) feature for toll free (800)
   or recorded/premium services (900) in North America predates the
   current Caller ID/CCS7 signalling methods. The caller's number could be
   delivered in terms of signalling tones (MF or multifrequency tones)
   included with the signalling tones used to set up the call to the
   800 or 900 number.

   As for the precise method of delivering the number to the called
   800 or 900 party, and more details on 800/900 ANI, the answer will
   need to wait for a future edition of the FAQ, or for a discussion
   in the Digest. Again, ANI was in service before caller ID and its
   equipment were commonplace.

   800 service customers can receive a list of calling numbers as part
   of the billing arrangements. This is only a monthly summary long after
   the calls were made, though, not a real-time caller number delivery.

Q: Is there some way I can use a modem to send text messages to my
   alphanumeric pager?

A: (courtesy J. Brad Hicks (mc![e-mail]))

   You will need two things:

   (1) The phone number of the modem lines at your paging vendor.  Keep
       pestering them until they let you talk to a real linesman or
       engineer; if they support text pagers, it's guaranteed that there
       is such a number.

   (2) A piece of software that supports the IXO/TAP protocol.

   There are a number of IXO/TAP software packages on the market. If you
   want to write your own, the protocol specification is in the Telecom
   Archives as IXO.TAP.protocol, along with some example code in HyperTalk,
   ixo.example.

Q: How can I prevent an extension from interfering with a modem call?

A: Modem connections are very sensitive to any sort of interference,
   including an extension that is picked up during a connection. The
   usual result is the loss of modem carrier, thus the end of the
   modem call.

   There are some recent Northern Telecom phones that have a light to
   indicate a line in use. While this will warn other extensions that
   someone else is on the line, it doesn't physically prevent an
   interruption on the used line.

   Physical disconnection of extensions could be attempted; switches
   in the wiring is one way to do this, as long as one remembers to
   switch the extension off when making a modem call, and to switch
   it back on when the line is available.

   The deluxe solution to this problem involves installing a PBX system.
   That way, each extension has a separate connection to the PBX first,
   before any extensions get to the outside line(s).

   Devices such as the RS Teleprotector can be connected into the
   phone wiring to provide an automatic means of preventing line
   interruptions.

Q: How does one maintain a phone call when hanging up on one extension,
   to pick up another extension?

A: The old PBX/key system feature called Hold is the way to maintain the
   call on the line while switching from one extension to another. The
   first extension is put on hold, then the other extension is picked up
   to continue the conversation.

   Assuming one doesn't want to spend much cash on an entire PBX system,
   a few residential phones on the market may have a "hold" feature. Old
   key telephone sets certainly will (if one finds the means to connect
   these types of phones into ordinary phone wiring).

---------
Numbering
---------

Q: What is a numbering plan?

A: This is a plan which establishes the format of codes and subscriber
   numbers for a telephone system or other communications system such
   as Telex. On a local level, subscriber numbers can have a certain
   number of digits (in some cases, the number of digits varies according
   to the exchange centre or digit sequence used). The local plan would
   allow for codes used to reach operators, directory assistance, repair,
   test numbers, etc. On a regional or even national level, there need to
   be area codes or number prefixes established in order to route calls
   to the appropriate cities and central offices.

   The typical pattern is to use local numbers within a region, and use
   an STD (subscriber trunk dialing) or area code to call a number in
   another region. The most common method is to use numbers beginning with
   0 as a long distance or inter-regional access digit, followed by other
   digits to route to the proper city (e.g. within the UK, dial 0171 or 0181
   for London, or 0121 for Birmingham). Digits other than 0 (generally 2
   through 9) would then represent the initial digit of local numbers.

   In France, there are currently two areas; Paris and everything else.
   All local numbers in France have eight digits. Paris uses an area code of
   1, the rest of the country has no area code as such (just the local
   number, which does not begin with a 1). Long distance access is 16 plus
   the number for regions outside Paris, or for Paris, access is
   16 + 1 + Paris number (this is expected to change to 0 + 1 + number,
   consistent with most of Europe). All areas of France are expected to have
   a single-digit area code in service by 1996; Paris will retain its area
   code of 1, but areas outside Paris will have a new area code assigned to
   the 8-digit local numbers. The "16" long distance prefix would no longer
   be used and calls within France would be dialed as 0 + area code
   digit + 8-digit number.

   Some countries do not use an area code; instead, the local number is
   unique within the country. This typically occurs in small nations but such
   schemes are found in Denmark and Singapore. Hong Kong got rid of its area
   codes some years ago and converted to seven-digit local numbers, which
   subsequently became an expanded 8-digit local number system in 1995.

   North America uses a fixed-length numbering plan. Area codes always
   have three digits and local phone numbers seven. A separate '1' prefix
   is dialed for long distance calls (that is, 1 + area code + number).

   Mexico has variable length area codes, but the total number of digits
   in the area code and local number is a constant 8 (e.g. Mexico City area
   code 5 + 7-digit number, or Ciudad Juarez area code 16 + 6-digit number).
   '91' is the standard direct dial prefix within Mexico (e.g. long
   distance within Mexico is dialed 91 + area code + number).

   Some nations such as Germany have an almost unpredictable variability
   in area code and local number length. The number of digits in local
   numbers can vary even within an area code.

   Many countries include the prefix in their STD codes listing (0121
   Birmingham, UK; 90 Helsinki, Finland (to be changed to 09 in 1996)).
   Including the initial 0 or 9 may be convenient domestically, but these
   numbers have to be removed when numbers are dialed from other nations.

Q: Who has authority over numbering plans?

A: This is up to each country; in those nations with a monopoly telephone
   carrier, this could be administered by the telephone company or a
   government agency (noting that in many cases, the telco is a government
   agency anyway). In those nations having competing carriers, governments
   tend to wind up setting the rules, if not administering the numbering
   resources themselves.

   In the United States, the Federal Communications Commission (FCC)
   oversees American telephone numbering and has ultimate authority.
   Original area code assignments and numbering plan structure were
   devised by the original AT&T monopoly system.

   Following the break-up of AT&T, Bellcore (a non-governmental company
   owned jointly by the major Bell Regional Holding Companies) assigned
   the area codes and assumed duties as the North American Numbering Plan
   Administrator.

   Bellcore recently advised the FCC that it would relinquish its role
   as the North American Numbering Plan Administrator. In its place is
   to be an industry oversight organization consisting of various
   telecommunications interests. This move is intended to avoid the
   impression that numbering plan decisions are controlled by a particular
   segment of the telecommunications industry.

   In the United Kingdom, Oftel is the organisation responsible for
   numbering plan issues. The "Phoneday" arrangement, where the digit
   '1' was added to geographic area or STD codes, was an Oftel decision.

   Industry Canada (formerly Communications Canada) is the government
   agency having ultimate legal responsibility over the Canadian numbering
   plan, which for all practical purposes is the adoption of the North
   American Numbering Plan. A Canadian Numbering Administrator maintains
   and co-ordinates numbering assignments such as long distance carrier codes.

   In Bermuda and those Caribbean nations under the North American Numbering
   Plan, Bellcore has been the authority for telephone numbering assignments
   within the 809 area code. However, area code splits such as the one
   assigning NPA 441 to Bermuda could allow the individual nations to
   assume numbering administration. Whether this will happen is unknown.

Q: How was the country code system developed?

A: In the early 1960s, a global numbering plan was devised so that the
   various national telephone systems can be linked; this used country
   codes of one to three digits in length, assigned according to geographic
   regions on the Earth. In fact, the system was developed from a numbering
   plan already devised for Europe. International Telecommunications Union
   (ITU) documents from that time showed a numbering plan of two-digit
   country codes covering Europe and the Mediterranean Basin countries and
   even described at that time the overseas access codes to be used in
   various countries (France 19, UK 010 - most of these codes were in use
   for many years thereafter). Many country codes from that original
   numbering plan were used in the worldwide plan such as France 33,
   UK 44 although many codes had to be renumbered for the new worldwide plan.

   The world numbering zones (representing the initial country code
   digits) are:

       1        North America
       2        Africa
       3 and 4  Europe
       5        South/Latin America (includes Mexico)
       6        South Pacific countries, Oceana (e.g. Australia)
       7        Commonwealth of Independent States (former USSR)
       8        East Asia (e.g. Japan, China), plus Marisat/Inmarsat
       9        West & South Asia, Middle East (e.g. India, Saudi Arabia)

   There are a few anomalies to the zoning; St Pierre & Miquelon, a French
   territory near the Canadian province of Newfoundland, was issued a
   country code in zone 5 (country code 508), since North America already
   has the country code 1, and there were no codes available in zones 3 or
   4 (at the time of original assignment). There was room in world zone 5
   for the code. Similarly, Greenland (country code 299) could not be fitted
   into the European zones. 299 was a code that was available from another
   zone (Africa) that was numerically close.

   ITU-T policy is that new country code assignments will be three digits.
   Country codes for new types of international services, such as toll-free
   country codes, are to be assigned from the world zone with the most
   unassigned country codes (currently zone 8, meaning special services
   will have country codes beginning with 8). There is some talk of
   assigning the available country code 800 for an international toll-free
   service (though this might be confused with national toll-free services
   that already use an 800 area code).

   The TELECOM Digest Archives has country code listings, including a
   detailed set which indicates area/STD codes used within country codes
   as they would be dialed in international dialing (excluding domestic
   inter-regional prefix digits).

Q: What is the correct way to write a telephone number for
   international use?

A: The method recommended by the ITU-T (formerly CCITT) is set forth in
   Recommendation E.123. International format numbers use the plus sign
   followed by the country code, then the STD code if any (without common
   STD/area code prefix digits or long distance access digits) then the
   local number. The following numbers (given for the sake of example
   only) describe some of the formats used:

    City             Domestic Number    International Format
    ---------------  -----------------  --------------------
    Toronto, Canada  [phone]     + 1 416 872 2372
    Paris, France    (1) 33.33.33.33    + 33 1 33 33 33 33
    Birmingham, UK   [phone]    + 44 121 123 4567
    Colon, Panama    441-2345           + 507 441 2345
    Tokyo, Japan     [phone]     + 81 3 4567 8901
    Hong Kong        2345 6789          + 852 2345 6789

   In most cases, the initial 0 of an STD code will not form part of the
   international format number. Some countries use a common prefix of 9
   (such as Finland or Colombia). Some countries' STD codes can be used
   as they are where prefix digits are not part of the area code (as is
   the case in North America, Mexico, and a few other countries).

   As indicated in the above example, country code 1 is used for the
   U.S., Canada and many Caribbean nations under the North American
   Numbering Plan (NANP). This fact is not as well-publicised by American
   and Canadian telephone companies as it is in other countries. Note
   that 1 is dialed first in domestic long distance calls; that this is
   identical to country code 1 is a coincidence.

   The important consideration is that the digits following the +
   represent the number as it would be dialed on an international call
   (that is, the telephone company's overseas dialing code followed
   by the international number after the + sign).

Q: What are the access codes used in international dialing?

A: This depends on the country from which an international call is placed.
   The most common international prefix is 00 (followed by the international
   format number), which most countries have adopted or are planning to
   adopt. An ITU-T Recommendation specifies 00 as the preferred code. The
   European Union nations in particular are adopting 00 as the standard
   international access code. Those EU nations not already using 00 will
   soon do so.

   Toby Nixon of Microsoft ([e-mail]) maintains a full list of
   these international access codes. These are occasionally posted as Digest
   articles (with a recent posting being in Digest v15 #480).

   Some of the current or recent exceptions to 00 are:

     Australia @    0011            Mexico +          98
     Canada         011             Norway @          095
     Colombia       90              USA               011
     Denmark @      009             Russia            8 W 10
     Finland @      990             Spain @           07
     France @       19 W            Nigeria           009
     Ireland        00 (was 16)     Papua New Guinea  05
     Japan          001             Sweden @          009

   W = wait for another dial tone before proceeding with rest of number
   + = Mexico uses 95 to access North America (country code 1) specifically;
       98 is used for calling other nations
   @ = Indicates reported plans to switch to 00 within a few years,
       if not already.

   Netherlands was 09 W until its recent conversion to 00.

   United Kingdom adopted 00 as the international access code in 1995,
   replacing the 010 access code.

   Turkey replaced its old 9 W 9 international access with 00 recently.

   Romania recently overhauled its numbering plan, converting to 00
   for international access in the process.

Q: What does NPA, NNX, or NXX mean?

A: NPA means Numbering Plan Area, a formal term meaning a North American
   area code (like New York 212, Chicago 312, Toronto 416 etc.).

   NNX refers to the format of the telephone number's prefix or central
   office code (the first three digits of a seven-digit local North
   American number). The N represents a digit from 2 to 9; an X represents
   any digit 0 to 9. Thus, NNX prefixes can number from 220 to 999, as
   long as they do not have a 0 or 1 as the middle digit.

   NXX means any prefix/central office code from 200 to 999 could be
   represented, allowing for any value in the middle digit. Obvious special
   exceptions include 411 (directory assistance) and 911 (emergency).

Q: What happens when all the telephone numbers run out in a given area?

A: With demand for phone numbers increasing worldwide, the capacity given by
   a certain number of digits in a numbering plan will tend to be exhausted.

   In whatever country, capacity expansion can be done by such measures as
   adding an extra digit to the local number (as was done in Tokyo, Japan
   or in Paris, France). Area code numbers themselves could also have extra
   digits added to increase the number of available area codes. See also
   the following question on "overlay" area codes.

   Area/STD codes can be split along geographic lines, such as London UK's
   split of the old 01 STD code into 071 (inner London) and 081 (outer
   London). These codes are now 0171 and 0181 respectively, as a result
   of yet another UK numbering change called "Phoneday".

Q: How long can a phone number be (internationally speaking)?

A: Internationally, telephone numbers may currently have up to 12 digits
   total for the combined country code, area code, and subscriber number.
   That is, an international call at present should have no more than 12
   digits after the international dialing code.

   The maximum number of international number digits limit will be increased
   to 15 digits total as of "Time T" (end of 1996), to allow for extra
   numbering capacity within countries, and to expand the numbering capacity
   for international calling.

   Some telephone numbers in Germany, for instance, are reported to exceed
   the current 12 digit international limit already. A few other countries
   may also have telephone numbers that exceed the current international
   maximum length. Such numbers may require manual operator handling in
   areas where switches are not already capable of doing so.

Q: What is "Time T"?

A: 31 December 1996, 2359 hours UTC (GMT), as referred to by ITU-T.

Q: What is an overlay area code?

A: An "overlay" area code is assigned to serve as a parallel code in an
   existing area code's territory. Cellular and pager services, for
   instance, could operate with an overlay area code distinct from the
   geographic (traditional phone service) area code(s) used in the region.
   Furthermore, many area code boundaries are becoming too small to
   practically subdivide in terms of geography.

   Overlay area codes are being implemented in the United States for
   dedicated use by cellular and pager services. Los Angeles originally
   had the 213 area code, and subsequently divided this territory with
   the 818 and then 310 area codes. Now, a new 562 area code will be
   the first overlay for this territory.

Q: How was extra numbering capacity achieved in North America?

A: Within an area code, there are a maximum number of prefixes
   (i.e. first three digits of a phone number) that can be assigned.

   In the original telephone "numbering plan", up to 640 prefixes
   could be assigned per area code (of the NNX format, 8 * 8 * 10).
   Yet, prefixes get used up due to growth and demand for new numbers
   (accelerated by popularity of separate fax or modem lines, or by
   new services such as the distinctive ringing numbers that ring a
   single line differently depending on which phone number was dialed).

   When the prefixes of NNX format run out, there are two options
   in order to allow for more prefixes, and in turn more numbers:

      1) "splitting" the area code so that a new area code is
         assigned to accommodate new prefixes, or

      2) allowing extra prefixes to be assigned by allowing NXX
         format instead of NNX format.

   The preferred option is to go with 2) first, in order to avoid having
   a new area code assignment. Yet, this gives the area code a maximum of
   160 new prefixes, or 8 * 10 * 10 = 800. When the NXX format prefixes
   are used up, then 1) is not optional. New York and Los Angeles are two
   regions that have gone from NNX to NXX format prefixes first, then
   their area codes were split.

   Interestingly enough, some area codes have split even though there was
   no change from NNX format prefixes to NXX at the time. Such splits have
   occurred in Florida (305/407) and Colorado (303/719). The precise reasons
   why a change to NXX-style prefixes was not done in those cases were not
   known, but switching requirements in those areas, plus telephone company
   expenses in changing from NNX to NXX format (and the likelihood of an
   eventual area code split) were likely factors in these decisions.

   Note that it is prefixes, and not necessarily the number of telephones,
   that determines how crowded an area code is. Small exchanges could use
   a whole prefix for only a few phones, while an urban exchange may use
   most of the 10 000 possible numbers per prefix. Companies, paging, test
   numbers and special services can be assigned their own prefixes as
   well, such as the 555 directory assistance prefix (555.1212).

Q: In North America, why did long distance dialing within area codes
   change so that 1 + home area code + number has to be dialed, or
   in some places change to just seven digits (like a local call)?

A: Originally, most areas of North America allowed long distance calls to
   be dialed as 1 + area code + number for calls outside an area code,
   while calls within an area code could be dialed as just 1 + number. A
   distinction between area codes (having 0 or 1 as the middle digit) and
   prefixes (middle digit cannot be 0 or 1) made this possible.

   When prefixes change to NXX, that means that the prefix numbers can be
   identical to area codes. The phone equipment is no longer able to make a
   distinction between what is an area code and what is a prefix within the
   home area code, based on the first three digits. For instance, it is hard
   for central offices to tell the difference between 1+210 555.2368 and
   1+210.5552, based on the first 8 digits dialed.

   Thus, 1 + area code + number for all long distance calls is used in
   many North American area codes. Or ... just dialing seven digits within
   the area code for all calls, local or long distance (thus risking
   complaints from customers who thought they were making a local call when
   in fact the call was long distance).

   To make room for more area codes, all areas in the North American
   Numbering Plan (NANP) made allowances in their dialing schemes for
   new "interchangeable" area codes (see following questions). The
   distinction between the area code and prefix (central office code)
   formats was lost for all area codes as of January 1995.

   It is up to each phone company to decide how to handle prefix and
   dialing changes. There are different rules from company to company.

Q: What is an "interchangeable" area code?

A: The interchangeable area code format refers to area code numbers that
   can be the same as prefix numbers. In other words, the new area codes
   with middle digits other than 0 or 1 are "interchangeable" in the
   sense that the area code and prefix numbers can now be the same.

Q: Why were "interchangeable" area codes introduced?

   There were a limited number of area codes available under the original
   North American format. Just prior to 1995, there were no longer any area
   codes that could be assigned from the traditional format other than a
   few special "non-geographic" codes (200, 300, 400). Some other special
   cases include 600 for Canadian Datalink/ISDN service, which began as the
   Canadian TWX (telco teletype) code. 600 was formerly 610, which is now
   in use splitting area 215 in the Philadelphia area. 710 is reserved for
   mysterious U.S. government services.

   Area codes ending in -00 are intended for special services like 800 or
   900 numbers. Also, -11 area codes could be confused with services like
   411 (directory assistance) or 911 (emergency); indeed, a few places
   use the non-standard 1+411 for directory assistance.

   Bellcore, while it was North American Numbering Plan (NANP) Administrator,
   set the January 1995 date at which interchangeable area codes were to
   become active. Given the unprecedented demand for new area codes,
   the original interchangeable deadline of July 1995 was a good guess
   when it was announced many years ago.

   The last vacant traditional-format area codes were 910 (split North
   Carolina's 919 area code) and 610 (Pennsylvania, split 215 Philadelphia).

   For some time, the plan was to assign new area codes that end in 0 (such
   as 220, 650, etc.). This would have allowed some area codes to retain the
   ability to dial 1+number (without dialing the home area code) for long
   distance calls within the area code, provided that they have not assigned
   prefixes ending in zero in conflict with new area codes. That scheme
   appears to have been abandoned in favour of assigning area codes with
   various third digits.

Q: Why not increase the number of digits in the North American
   Numbering Plan?

A: Some have suggested that the local numbers in metropolitan areas have
   8 digits rather than keep the 7-digit format and force the assignment
   of numerous area codes.

   The expansion plan for the NANP was set in the 1970s, if not earlier. The
   planners probably thought that keeping the area code and local number
   digit lengths was less disruptive and expensive compared to changing the
   length of the local number and/or area code. A uniform total number of
   digits in the area code and local number was probably thought desirable,
   also. The advent of interchangeable area codes means a huge increase in
   the number of available area codes, which should allow growth in the NANP
   for many years yet.

   Still, the plan does lead to some messy situations in metropolitan areas,
   which will be increasingly forced to adopt "overlay" codes. The result
   will force these areas to include the area code in dialing local numbers
   (i.e. ten-digit dialing), even to numbers in the same NPA, even across
   a street.

   The dynamics of today's growth in telephone numbering probably exceeded
   the wildest expectations of yesterday's telephone planners. Now, there's
   something of an NPA-of-the-Week club in effect.

Q: What "interchangeable" area codes been assigned?

A: The first known assignment was for Alabama: the existing area 205 was
   be split up, with a new 334 area assigned effective January 1995.
   Washington state's 206 area was subdivided to form the new 360 area
   (Seattle, the major population centre, kept the 206 area code). Chicago
   received a new 630 overlay area code, and Los Angeles a 562 area code.
   Arizona's 602 area also split, forming the new 520 area in March 1995.

   An NPA 456 was assigned for "inbound international" purposes, which will
   not be an active area code within North America as such; 456 will be used
   for calls from outside the NANP to select an international carrier for
   certain calls into North America.

   There are many new area code assignments, documented in Carl Moore's
   history of area codes document. This is available from the TELECOM
   Digest Archives. TELECOM Digest also carries postings announcing
   new area codes as they become known. Bellcore's website at
   http://www.bellcore.com/ also contains some information on announced
   area code assignments.

   Some documents regarding numbering plan issues have mentioned the
   need to distinguish between area codes that are geographic (regular
   telephone service within a given region) and non-geographic (800, 900,
   or other service not necessarily confined to a specific region). It
   appears the new non-geographic area codes are to end in double-digits
   (such as the new 888 toll-free code; thus 233 would also be a
   non-geographic code, as would the existing codes 500, 800, 900, etc.)

   Another plan originally called for the use of the area code's middle
   digit to determine whether an area code was geographic or not. Another
   issue is future expansion of the area code system that will be required
   if the NANP is to move beyond the current 3-digit NPA/7-digit number
   format.

Q: What about expanding area/STD codes in other countries?

A: Many countries tend to use variable numbers of digits in the local
   numbers and STD/area code numbers, thus there is often flexibility
   in assigning new codes or expanding the capacity of codes. Sometimes
   codes are changed to provide for extra capacity or to allow for
   a uniform numbering plan such as ensuring the total number of digits
   of the STD/area code plus the local number is constant within a
   country.

   In the UK, the digit '1' was added to most area codes as of 1995 in
   order to create extra STD code capacity. For instance, London's 071 and
   081 codes were changed to 0171 and 0181 respectively (internationally,
   this change was +44 71 and +44 81 to +44 171 and +44 181).

   France will change its system again, to divide the country into a few
   regions of single-digit area codes. Presently, Paris has an area code 1,
   with the remainder of France having no area code as such; eight-digit
   local numbers are used in and out of Paris. The areas outside of Paris
   would then get one-digit area codes corresponding to particular regions.

   Australia is converting to single digit area codes, with uniform
   eight-digit local numbers. This replaces the current system with
   variable-length area codes and local numbers. This new plan is being
   phased in throughout the 1990's. New Zealand also completed a change
   to single-digit area codes, with uniform seven-digit local numbers.

   Hong Kong actually got rid of its area codes a few years ago, replacing
   the few single-digit area codes with seven-digit (and now eight-digit)
   local numbers throughout Hong Kong. Then there's the anticipated
   1997 takeover by China, which likely means another international dialing
   change under China's country code.

Q: How are area codes assigned?

A: In many countries, an area code 1 (or 01) will be assigned to the
   capital city, or most populous city. There are exceptions, such as
   Mexico where Mexico City's area code is 5. Area codes of one or two
   digits (excluding embedded access digits such as the 0 of 01, say)
   will tend to be assigned to the largest cities, while area codes in
   smaller centres tend to have more digits.

   Some countries are modifying their numbering plans for various
   reasons. Sometimes this is done to increase numbering capacity (as
   mentioned earlier). Sometimes this is done to create a more consistent
   numbering plan so that telephone equipment can expect a predictable
   number of digits in national telephone numbers.

   A few nations use fixed-length area codes. Turkey recently established
   a three-digit national area code system. New Zealand moved to single-
   digit area codes, and Australia is in the midst of converting to a
   single-digit area code system.

   In country code 1 (U.S., Canada, much of the Caribbean) 212 and 213 were
   assigned to New York and Los Angeles respectively, likely because these
   area codes took the least amount of time to rotary-dial. A few other
   metropolitan areas also had shorter rotary-dialing properties (312
   Chicago, 313 Detroit). An area code like 907, on the other hand, took
   longer to dial on a rotary phone. The original plan was to use a middle
   digit of 0 where an area code covers an entire state or province, and
   middle digit 1 in states or provinces that have two or more area codes;
   this arrangement could not be maintained due to subsequent area code
   requirements.

   In the UK, an additional digit '1' was incorporated into the geographic
   area codes (e.g. London's 071 STD code became 0171). Area codes may
   still have varying numbers of digits, but the goal is to provide a fixed
   total number of digits in the area/STD code plus local number.

   Still, in other countries, this is not an issue if there are no area or
   STD codes used. The initial digits of a local number will determine the
   place or purpose of the number.

Q: What is Bellcore?

A: Bellcore, or Bell Communications Research, is a company that is jointly
   owned by the seven Bell Regional Holding Companies. That is, Bellcore
   assumed the duties of the Central Services organization in the old AT&T
   following its court-ordered breakup (known as the AT&T Consent Decree
   (Modified Final Judgment)). This was more commonly known as the
   divestiture that established widespread long distance competition in
   America.

   Bellcore develops and sells technical documents relating to the operation
   and use of the phone system, and does research and development on various
   communications technologies. For instance, Bellcore was involved in the
   MPEG video data compression method, designed to allow transmission of
   entertainment-quality video.

   Bellcore was actively involved in numbering plan issues, such as the
   assignment of area codes and long distance carrier identification codes.
   This activity, however, was to be transferred to a new North American
   Numbering Plan Administrator.

Q: How can I contact Bellcore?

A: The Bellcore document hotline (with touch tone menu) can be reached at
   1 800 521 CORE (i.e. 1 800 521 2673) within the USA and Canada, or
   [phone] in other nations ([phone] is the fax number).
   A catalogue of documents can be ordered through this number. General
   information is also available on WWW (http://www.bellcore.com/).

   For the voice menu on Bellcore's document hotline, to order a document
   press 2 at the automated greeting. If you want to talk to a person
   about availability, prices, etc, press 4 at the automated greeting.

   Payment for documents can be made using American Express, Visa, Master
   Card, International Money Orders, and Checks on US Banks. If you don't
   have a document number handy, a catalog of technical documents is available.

   Bellcore Technical Advisories (TAs) and other preliminary "advisories"
   are only available by writing:

     Bellcore
     Document Registrar
     445 South Street - Room 2J-125
     P. O. Box 1910
     Morristown, NJ USA 07962-1910

   The mailing address for ordering other "standard" documents (including
   Technical Reference ("TR") documents) is:

     Bellcore Customer Service
     60 New England Avenue
     Piscataway, NJ USA 08854-4196

   NPA/NXX (area codes, exchange codes) information is maintained by
   the (somewhat) separate Traffic Routing Administration (TRA) group,
   at [phone].

   For all other TRA "products", or information about on-line access to a
   database of routing data, contact the TRA Hotline at [phone],
   or write to:

     Traffic Routing Administration
     Bell Communications Research, Inc.
     435 South Street, Room 1J321
     Morristown, NJ  07962-1961

   If you want to talk to the "pub" folks, or a technical person, the
   numbers/addresses are in the front of any TR (and the "Catalog").

   Note that certain Bellcore documents (particularly certain TRA documents),
   require the signing of a "Terms and Conditions" agreement before purchase.

Q: How can I get exchange/billing data? What is a V&H tape?

A: Bellcore sells the NPA-NXX Vertical and Horizontal Coordinates Tape
   (the "V&H Tape"); this is primarily for billing purposes and lists
   (for each NXX, or central office code) the type of NXX, major/minor
   V&H coordinates (a sort of "latitude" and "longitude" used to calculate
   rate distances for long distance billing), LATA Code (identifying the
   U.S. long distance service area), the RAO (revenue accounting office),
   Time Zone, Place Name, OCN (telephone company identifier) and indicators
   for international dialing and "Non-Dialable".

   Other related Bellcore documents include:

   - NPA/NXX Activity Guide lists all NPA/NXX codes scheduled to be added,
     removed or "modified" (monthly). There's also an Active Code List that
     lists all NPA/NXX codes that aren't planned to be removed or "modified"
     for the next 6 months.

   - Local Exchange Routing Guide (LERG) contains information on all
     USA/Caribbean destinations, switching entities, Rate Centers and
     Localities, Tandem Homing information, operator service codes,
     800/900 NXX assignments, etc. (three 1600 BPI tapes). Mostly useful
     to interexchange carriers (IXCs) and other telephone companies.

   - Telephone Area Code Directory (TACD) is a document listing area
     codes according to location (ordered by state/province and place).
     TACD also includes a list of Carrier Identification Codes (CICs)
     used for 10XXX+ or 950.ZXXX long distance service selection.

   In other nations, the first place to ask would be the telephone
   company responsible for the local service, or the telecommunications
   regulatory administration.


--------------------
Regulatory & Tariffs
--------------------

Q: How are long distance call costs rated?

A: This depends on the country or region, and even long distance carrier.

   A common method of call rating depends on the "rate distance", a
   calculated distance between the originating exchange and the destination
   exchange. This is usually done on the basis of designated exchange
   locations on each end of the conversation. The exact customer telephone
   locations are not used as such a calculation would be too impractical
   (too many locations to keep track of, for one thing).

   Another form of rating depends on zones. Calls within a zone incur a
   certain rate, while calls to other zones incur different rates. Some
   long distance carriers may assess a constant rate per minute for all
   domestic long distance calls, at certain times, regardless of where the
   call originates and terminates.

   Telephone directories of some nations may include a table that provides
   all the ratings between points, depending on the area or STD codes
   involved. Such ratings normally correspond with distance between the
   main centres represented by the STD/area codes.

   North America

   Within North America, rate distance is calculated using the "V&H" system.
   V stands for "vertical" (north-south position) and H for "horizontal"
   (east-west position). Each exchange is represented by a location expressed
   as a V&H co-ordinate. A rate distance can be calculated from two V&H
   co-ordinate sets based on Pythagorean Theorem, i.e. rate distance =
   sqrt((V1-V2)^2+(H1-H2)^2)/10 where (V1,H1) is the V&H for one end of a
   call, and (V2,H2) represents the other end of a call.

   The V&H system was based on the Donald Elliptical Projection, named after
   Jay K. Donald of AT&T who created this method in 1956. The idea is to
   "flatten" the Earth - a calculation based on a flat plane is easier than
   doing the trigonometry on those degrees, minutes and seconds of latitude
   and longitude. Two other references to this work include "V-H Coordinate
   Rediscovered" by Eric K. Grimmelmann, Bell Labs Technical Memo, September
   1980 and some notes by Jay Donald 17 January 1957. An internal Bellcore
   memo on the subject by Ashok Ingle was also reported.

   Conversion between latitude-longitude and V&H systems is possible. A C
   program to determine V&H from latitude-longitude was posted in TELECOM
   Digest V15 #362 (an episode that contains other useful discussion of
   V&H). Other conversion programs are not widely known or are privately
   created.

   A program called NPA by "PC Consultant" in Houston provides V&H
   information to map NPA-NXX (central office codes) with zip codes, place
   names, etc. This is a shareware program that has been distributed via
   Compuserve and possible via web or FTP sites; it should be available at
   least in DOS and Windows versions. There may be other software packages
   available with such features, however.

   Other Nations

   For other nations, rate calculations may be available in long distance
   tariffs. Availability and accessibility of such tariffs will depend on
   the countries and companies involved. Distance and time are the normal
   factors of charging a call.

   While North America most often bases its long distance charges for
   each minute, or each 6 seconds for some services, some other countries
   use a meter pulse - a set charge is incurred for each pulse. The more
   costly the call, the more rapidly pulses occur.

   Wireless/Cellular Call Rating

   For wireless rating, the issues become more complex. In a cellular
   system, one might expect an "airtime" component that depends on the time
   used by a cellular phone as it communicates with a base station. This
   could not depend on distance since current systems cannot pinpoint the
   exact location of a cellular phone. For local and long distance, a
   "landline" charge component, usually based on wireline call ratings,
   would be added, depending on the base station through which a call takes
   place. Exact information on wireless call rating can be obtained from the
   companies involved (at least sometimes).

Q: What's this about the FCC starting a modem tax for those using
   modems on phone lines?

A: Much of the "modem tax" talk of recent years has been of the tall urban
   legend variety, on the order of the Craig Shergold story (yes, folks,
   Craig's doing okay as of last report and he doesn't need cards of any
   kind). It started when the FCC took up a proposal that, if it had passed,
   would have raised the rate that certain modem users paid, notably those
   who have set up their own long distance networks for public use, like
   Compu$erve. The proposal was not enacted into law.

   Local exchange companies levy "access charges" for use of the local
   network by long distance carriers. "Enhanced service providers" (ESPs)
   or services acting on the nature or content of customer provided
   information, or which permit user interaction with stored information,
   are exempt from such access charges and can obtain local service at
   constant monthly usage insensitive rates (where available). The "modem
   tax" would occur if the ESP exemption were to be removed.

   Nevertheless, tales of rate increases and modem taxes could come up
   again in the future. Here's how to tell the facts from the urban
   legends. (1) Demand documentation; don't act until you see a copy of
   the FCC proposal. (2) Once you have the proposal, look at the number.
   It will be in the form yy-n, yy-nn, or yy-nnn. The first number, before
   the hyphen, is the year. If, for example, it's the infamous 85-79, you
   know it was the 79th proposal all the way back in 1985, and no longer
   matters. (3) If you do see an up-to-date proposal, read it carefully.
   If you can't tell what part of it enacts a "modem tax", demand that
   the person who wants you to act explain it to you. If they can't, or
   won't, then (and only then) bring it up on Telecom Digest, making sure
   that you always include the FCC proposal's number, so that people know
   which document you're talking about.

   One report from Massacheusetts reports of proposals to charge state tax
   on any user fees collected for bulletin boards or on-line services. (The
   stated reference of state law is 830 CMR 64H.1.6 for those wanting to
   confirm or deny this information). Those running no-charge BBSes should
   not be required to charge tax on a zero cost, though.

   Regulators in other countries may also have similar types of notices. The
   CRTC in Canada issues public notices and decisions on telecommunications
   using similar numbering schemes. Hoaxes such as fax/modem line surcharges
   and imaginary BBS licencing threats have surfaced in recent months; all
   of these have proven to be unsubstantiated.

Q: Why is a touch tone line more expensive than a rotary dial
   line (in many places)?

A: This has been an occasional debate topic in the Digest. Indeed, there
   can be a surcharge from $1 to $3 per month to have the ability to dial
   using touch tone.

   The tone surcharge is a holdover from the 1960's, when this technology
   was introduced. Originally, decoders would be incorporated into crossbar
   exchanges, or tone converters added to step-by-step switches. The tone
   surcharge thus reflected the costs of the technology that was available
   at the time. Today, cheap integrated circuits are readily available for
   tone decoding and are a standard part of today's electronic switching
   systems. Tone detection costs are thus negligible (and some would argue
   tone detection saves costs), and in fact is easier for the phone company
   to administer than the old pulse/rotary dialing methods.

   Today's technology generally fails to warrant these tone surcharges.
   The continued use of these surcharges, then, may be in order to allow
   LECs to retain a revenue stream without appearing to increase rates for
   basic local service. Regulators have allowed the process to continue.

   Some have suggested tone dialing charges reflect the value of a demanded
   service; tone is better, thus a premium is claimed for this perceived
   privilege. Widespread acceptance of tone dialing today makes this appear
   to be less of a luxury than in the past, however.

   Some telephone companies have abandoned a premium charge for tone
   dialing by including this in the regular local service charge. Others
   may be phasing out the tone surcharge and adjusting local rates to
   reflect conversion of all customers to tone dialing. Others still
   collect some form of tone surcharge.

Q: How come I got charged at a hotel for a call where no one answered?
   Why is the timing on some of the long distance carriers inaccurate?

A: Where actual call supervision is unavailable or inconvenient, some call
   billing systems will guess when a call might be answered. That is, a
   customer dials the call, and the equipment times the progress; after a
   certain point in time the billing will commence whether or not the party
   at the other end actually answers the phone. Thus, calls left ringing for
   more than five or six rings can be billed. Adding to the problem is the
   fact that calls don't necessarily start ringing at a fixed time after the
   last digit is dialed.

   Needless to say, some calls can be left uncharged in this scheme. Should
   the call be answered and completed before the billing timer elapses,
   the call won't be billed.

   There are reports that California requires proper billing and supervision
   of calls. Other areas may adopt similar requirements. Technological
   advances, consumer demand and regulation changes should make the stories
   of inaccurate call billings a thing of the past.

Q: What is AT&T Tariff 12?

A: The long distance carrier AT&T uses a "Tariff 12" pricing to set up a
   special deal with specific companies. These tariffs are set up so that
   the company for which the deal is made is not named, but its
   telecommunications situation is described in detail. This means that any
   other company that has a similar situation is also entitled to the same
   custom provisions.

   Tariff 12 deals are the subject of occasional scorn from competing
   carriers. The non-AT&T companies do have freedom to offer custom deals
   of their own, however. AT&T still has the majority of the long distance
   market, and the after-effects of the former monopoly service linger.
   Concerns remain regarding AT&T's apparent market dominance, prompting
   continued regulatory checks and balances for now.

Q: What are the ITU and CCITT?

A: ITU is the International Telecommunication Union, the Geneva-based
   United Nations agency dealing with international telecommunications
   standards.

   CCITT (the French acronym for the International Telegraph and Telephone
   Consultative Committee) is the former telecommunications standards body of
   the ITU. CCITT is now known as the ITU Telecommunication Standardization
   Sector (ITU-T) effective 1 March 1993.

   Other former ITU divisions (prior to the 1993 changes) besides CCITT
   included the General Secretariat, the International Frequency Registration
   Board (IFRB), the International Radio Consultative Committee (CCIR),
   and the Telecommunications Development Bureau (BDT). (Note that some
   of the abbreviations in ITU correspond to the French language names).

   The new ITU organisational structure includes the Radiocommunication
   Sector (ITU-R) and the Telecommunication Development Sector (ITU-D)
   as well as the previously-mentioned Telecommunication Standardization
   Sector (ITU-T). ITU-T includes the standards making activities of the
   former CCITT and CCIR. The former BDT's activities now fall under the
   ITU-D jurisdiction.

   The World Telecommunication Standardization Conference (WTSC) (formerly
   CCITT Plenary Assembly) makes the decisions regarding international
   telecommunications standards. Standards for such things as international
   directory assistance handling, country code numbering, and other
   technical matters are decided by the WTSC. The former CCITT Plenary
   Assembly published volumes of these standards every four years, with
   each session's volumes identified by a colour. The 1988 Blue Books were
   the last ones to be published from a Plenary Assembly, after which a
   decision was taken not to continue the publication of standards in this
   format. Recommendations are available separately, and updated as needed.

   Standards are referred to as Recommendations such as ITU-T Recommendation
   X.400 regarding electronic mail, or E.164 regarding international
   telecommunications numbering. (These were formerly referred to as
   CCITT Recommendations; anything that was a CCITT Recommendation
   automatically became an ITU-T Recommendation).

   ITU's Telecommunication Standardization Bureau (TSB) replaces the
   function of the former CCITT Specialized Secretariat.

-----------
Competition
-----------

Q: Which countries have competitive telecommunications services?

A: Originally, local and long distance telephone services were provided
   by a monopoly whether this was under private or government ownership.
   Today, deregulation of telephone companies and telecommunications is a
   worldwide trend. For better or worse, the international marketplace is
   demanding more innovation and competition in telecom markets in such
   areas as electronic mail, fax and data services as well as the long
   distance, satellite and other network services.

   United States:

   Competition in long distance services began in the early 1980s with the
   court-ordered dissolution of the Bell System into such pieces as regional
   local telephone providers, AT&T (long distance) and Bellcore (research,
   administration of telephone standards, etc.). Today's choice of carriers
   include: AT&T, MCI, Sprint, LDDS (which bought Metromedia/ITT and ATC,
   and more recently WilTel), Cable & Wireless, and Allnet.

   Competing local network plans were recently established. Companies such
   as networkMCI are expected to provide alternative local services in
   a growing number of markets.

   United Kingdom:

   The UK had a duopoly long distance situation: British Telecom and Mercury
   provided long distance services. Effective with a 1991 UK Government White
   Paper, more carriers were allowed to provide local and long distance
   services. These include Energis, Ionica, ACC, WorldCom, City of London
   Telecommunications, MFS (UK), Millicom and others. BT and Mercury hold
   the only licenses to provide facilities based international service using
   undersea cables, although most resale is virtually unregulated.
   International satellite services not interconnected into the switched
   network may also be provided by virtually any party.

   Canada:

   Canada permitted public long distance competition in June 1992. Prior to
   that, there was limited competition in terms of such things as fax
   communication services and various long distance/local service resellers,
   aimed at business interests. Unitel and BCRL/Call-Net (now known as
   Sprint Canada) were successful in their application to compete. A
   subsequent appeal of certain aspects of this decision was made by Bell
   Canada and other existing telephone companies. The decision withstood
   this appeal, finally permitting full-scale long distance competition.

   Local service competition was declared open by the Canadian regulator
   (CRTC) late in 1994. No significant plans have yet been announced to
   provide new local services, other than some cable company Internet
   access service. Some specialty business services such are available.
   There was at least one university student residential local service
   established, competing with Bell (at York University).

   Mexico:

   Mexico reportedly is opening competition in long distance services
   by the late 1990s.

   New Zealand:

   New Zealand now allows free entry into telecommunications. Any party
   wishing to establish a network may apply to be a registered network
   operator. Clear Communications is one notable New Zealand long distance
   competitor.

   Australia:

   Optus was the first long distance competitor effective 1992. It is
   licensed to compete with Telstra (the former monopoly) in local,
   national, international and mobile services (although not much local
   competing service is reported yet). Vodafone is another competitor in
   the mobile market.

   Japan:

   Domestic long distance competition since the mid/late 1980's consists
   of NTT (Nippon Telephone and Telegraph, the former national monopoly),
   Japan Telecom and Teleway Japan and DDI. A triopoly exists for
   international services: KDD (former international monopoly), IDC and
   ITJ. NTT operates most local service.

   Finland:

   Public long distance competition was permitted in January 1994. Prior to
   that, in the 1980's, there was limited competition on fax and data
   communication services offered via the telephone network. International
   competition began July 1994. Domestic long distance is provided by
   Tele (Telecom Finland), NN9 and Telivo Oy. Finnet and Telivo are
   competing for international calling. Local area competition has been
   started with both wire telephones and digital DECT handsets.

   The cellular telecom market has the most subscribers in the world per
   capita, with tough competition in the digital GSM system. The
   telecommunications market (national services, including mobile)
   is provided by Tele and the Telegroup of Finland, the latter of which
   consists of 47 local telecom operators. Radiolinja is a mobile
   services competitor since 1990.

   Europe:

   There is a directive within the European Union that member nations are
   to allow a certain level of communications competition by 1998. Long
   distance competition, at least, will eventually be established in
   those member nations.

   International and mobile communications in France have long been
   open to competition, although the local and long distance services
   are still only available as a monopoly service for now.

   Other nations:

   Hong Kong is in the process of offering local licences to compete with
   Hong Kong Telecom (due to start 1 July 1995).

   India called for bidders for local licences to compete with the
   Department of Telecommunications (DoT) on 16 January 1995.

   Many Asian nations are expected to develop telecom competition: Korea,
   Vietnam and Singapore are nations to watch. China may develop a
   competition between two government monopolies, if certain reports
   are correct.

Q: What is a COCOT?

A: Customer-Owned Coin-Operated Telephone, or perhaps Coin-Operated
   Customer-Owned Telephone. Essentially, this is a privately-owned public
   telephone as opposed to the traditional payphone that is owned and
   operated by the local telephone company. Most COCOTs exist in the United
   States; their status is not too well-known outside the U.S. Certainly
   there are no approved COCOTs in Canada as such and they are also likely
   rare or nonexistent in other nations.

   The COCOT is the target of much scorn as it often delivers less than what
   one would hope for in competition. Cited deficiencies of many of these
   units include prohibiting access to carriers like AT&T, use of default
   "carriers" that charge exorbitant rates for long distance calls, etc.
   Some of them have had problems when newly activated area codes were used.
   In some cases, COCOTs would not even place calls to numbers whose new
   area codes could not be dialed and whose old area codes could no longer
   be dialed.

Q: What is an AOS?

A: AOS is short for Alternate Operator Service. That is a company other
   than a long distance carrier or local telephone company that provides
   operator assisted services for long distance (collect, third number
   billed calls, person-to-person, etc.). Normally this involves having
   operator staff handle billing and the necessary dialing, but the AOS
   companies make use of existing long distance services rather than have
   their own network. Using an AOS, whether for a collect call or credit
   card call, can be more expensive than bargained for.

   Often, COCOTs (see above) will have their default "carrier" set to
   an AOS, for optimum revenues. Hotels may also set up phones to use
   AOS services by default.

Q: What is "splashing"?

A: Suppose you place a call from city A to city B using an AOS based in
   city C. The call is considered to be "splashed" if the billing for the
   call is based on the distance between city C (AOS) and city B
   (destination) rather than between cities A and B as one traditionally
   expects such calls to be billed. Thus, if the splashed distance (C-B)
   is much longer than the origin-destination (A-B) distance, the customer
   may be charged extra money. Of course, if the AOS city is close to the
   called party's location, the charges could be less than what might be
   normally expected. In any case, splashing causes a distortion of the
   normal long distance rates.

   Splashing in the United States is illegal according to the federal
   Telephone Operator Consumer Service Improvement Act.

Q: Where can I find a list of equal access (10XXX) codes?

A: The TELECOM Digest Archives has lists of these codes. They are contained
   in the files occ.10xxx.access.codes and occ.10xxx.list.updated in the
   TELECOM Digest Archives. New information on these codes or other access
   codes occasionally appears in TELECOM Digest.

   A Carrier Identification Code (CIC) is the XXX portion of a 10XXX code
   that identifies the long distance carrier in the United States and
   Canada. The 950.XXXX carrier access numbers also incorporate the CIC.
   That is, 10999 and 950.0999 would represent the same carrier.

   Note that 10XXX codes will soon become 101XXXX codes to allow for more
   carrier assignments. This format will be phased in over the next few
   years, allowing both old and new codes to be used temporarily. The
   101XXXX format may already be active in certain areas.

   The FCC issues these Carrier Identification Codes (CICs) and as such would
   maintain an official list of these. Bellcore also offered publications
   that contain CIC lists; one such list was included in the Telephone Area
   Code Directory (TACD) publication. (see "How can I contact Bellcore?"
   question for details on purchasing Bellcore documents).

   In Canada, a list of CICs used by Canadian carriers is maintained by
   the Canadian Numbering Administrator, part of the Industry Canada
   government department. These are co-ordinated with the U.S. CICs and
   thus should not conflict with U.S. assignments (although there are
   a few companies that have CICs assigned for use in both Canada and
   America).

Q: How can I tell who my default carrier is (or which carrier belongs
   to a 10XXX+ code)?

A: In most areas of the U.S. and Canada, dial 1 700 555.4141 to get a
   recording indicating the default carrier. This should be a free call.
   From regular lines, dialing 10XXX + 1 700 555.4141 should yield the
   identifying recordings of other carriers in most cases. Note that
   some carriers are not available in all regions, and that some carriers
   do not set up a recorded identification message.

   There are reports of telephone lines in the U.S. that have no default
   carrier. Each long distance call thus requires the selection of a
   specific carrier with a 10XXX code.

   Default carrier identification in other nations was not available
   for this FAQ. This depends on how each nation sets up the numbering
   plan to accomodate competing carriers, and whether a default carrier
   system is established.

   On U.S. payphones, AT&T is normally a "default" carrier for coin calls,
   but not necessarily so when it comes to calling/billing card numbers,
   collect calls or other operator-assisted calls. This explains instances
   where AT&T's recording is heard regardless of what carrier access codes
   are used before 1 700 555.4141.

   There can be exceptions to the AT&T only rule, such as the arrangement
   of New Jersey Bell, which is not only a local telco but also a regional
   long distance carrier. Their 10652 (or 10NJB) equal access code can
   be used at payphones, and for inter-LATA calls from certain New Jersey
   points to New York City and Philadelphia.

   COCOTs usually handle coin calls with self-contained coin billing
   equipment (and guessing the call connection time).

Q: What is a LATA?

A: LATA means Local Access Transport Area. This is a geographical area
   defined in the United States to determine whether the local telephone
   company handles long distance traffic, or whether this must be routed
   to an inter-exchange carrier such as MCI, Sprint, AT&T, etc. Some LATAs
   consist of an entire state, others consist of a part of a state (and
   sometimes a few exchanges in adjacent states).

   Recently, competing carriers have been permitted in some areas to handle
   long distance calls within the same LATA. The trend towards intra-LATA
   competition is bound to continue as technology and regulation permit.

   In Canada, there was no concept of LATA when full-scale long distance
   competition was introduced in 1992. That means competing carriers
   or local telephone companies can handle and bill long distance calls
   regardless of call origins and destinations.

Q: Where can LATA maps be found?

A: The BOC Notes on the Intra-LATA Networks publication by Bellcore
   (at least the 1986 version) had some state maps outlining the various
   LATAs and their boundaries.

   Some phone books indicate which exchanges are in a LATA, sometimes
   with a map that indicates the boundaries of LATAs within a state.

   CCMI (Center for Communications Management Information) also sells
   LATA maps. (CCMI can be contacted at 800 929.4824).

   McGraw Hill's business publishing division reportedly printed a LATA map.


--------
Features
--------

Q: What is the calling card "boing" and what is it made of?

A: When a North American call is dialed as 0 + area code + number, a
   "boing" is heard after the number is dialed. This is the prompt to
   enter a telephone company calling card number to bill the call with,
   or to select the operator (0) for further handling, or in some regions
   to specify collect or third number billing for the call.

   The boing consists of a very short burst of the '#' touch tone, followed
   by a rapidly decaying dial tone. The initial '#' tone is used in case
   certain tone-pulse converters exist on the line; such converters use the
   '#' to disable conversion of tones to dial pulses, a conversion which
   would prevent card number entries from reaching the long distance provider.

Q: What are codes like *70?

A: Such codes are used to activate and deactivate telephone features
   (eg. Call Waiting or Speed Calling). The format of these codes in
   North America is *xx (where xx represents two digits), which soon
   may be expanded to *xxx (three digits after *).

   In the UK and other nations, the codes may look like #43* or *55*, for
   example. Even within North America, there have been regional variations
   such as 72# (or on a pulse/rotary phone, dial 72 then wait).

   Since these feature codes vary from nation to nation (and sometimes with
   slight differences within the same nation), a comprehensive list is not
   provided in the FAQ at this time. Check local telephone directories or
   telephone company offices for information on the codes used in a specific
   area.

   The North American *xx codes were referred to as "Vertical Service
   Codes" in at least one Bellcore document.

Q: How can one dial *70 on a non-touch-tone (pulse/rotary) phone?

A: In North America at least, 1170 can be used in place of *70.

   Generally, use 11 on rotary/pulse phones to replace the * when
   using special feature codes.

Q: How can I prevent the call waiting tone from beeping in
   mid-conversation?

A: If you place the call, and don't want to get interrupted, a call
   waiting suppression code is dialed before dialing the call itself.
   The most common code for this in North America is *70 or 1170 (on
   rotary dial phone lines). 70# (or 70 and wait on rotary phone) could
   also be used in some areas. Other countries will have special codes
   for this (like #43# in the UK), and will vary in terms of capabilities
   offered.

   Local phone companies in some areas charge installation and monthly
   fees for 'Cancel Call Waiting', and you must subscribe for this to
   work. In some areas it comes free with Call Waiting. In a few other
   areas it may be unavailable at any price.

   Thus, to call 555.0000 so that call waiting is disabled, dial *70
   (or whatever the correct code is for your area), wait for another
   dial tone, then dial 555.0000 as usual.

   Suppressing call waiting tone on an *incoming* call may be possible
   depending on how your phone company has set the central office.
   One way of doing this is would be to flash your switch-hook briefly,
   check for a dial tone, then try dialing the call waiting suppress
   code (*70 or whatever). Southwestern Bell, for instance, uses a
   variant of this: <flash hook> *70 <flash hook> (i.e. a second hook
   flash required). The methods are not guaranteed, however; your phone
   company might be able to give a better answer if the preceding
   doesn't work.

   NOTE: each phone company will determine the capabilities of Call Waiting
   features, and what codes will be used to activate them, and what costs
   the service will be provided at. The codes are not necessarily the same
   from place to place. Please consult your phone company for official
   information in your particular area if any of the above codes do not work
   properly. Also check the phone book introductory pages as these sometimes
   include instructions on how to use special calling services such as
   Call Waiting.

Q: What is distinctive ringing?

A: First, distinctive ringing is a feature that offers extra numbers
   which cause different ringing patterns on a line. When the main number
   is called, the called party will receive the normal ringing pattern.
   If one of the extra numbers is dialed, that line would ring with a
   different cadence. In North America, the normal ringing pattern is
   a single ring every six seconds. The distinctive ring patterns are
   1) two short rings every six seconds, or 2) a short-long-short ring.

   Different ringing patterns are also used in conjunction with such
   features as busy call return, to indicate a freed line. One test
   done by Bell Canada set up a special ringing pattern (different from
   any of the featured distinctive rings) to indicate an incoming
   long distance call.

   Each telephone company has its own name for this feature: Ident-a-Call,
   Teen Ring, Feature Ring, etc. In any case, different ringing patterns
   allow for calls to certain people, or to sort out different call
   purposes such as for voice, fax, modem, or answering machine.

   Here are some companies that may offer devices that detect distinctive
   ring patterns and route calls to distinctive lines; these are for the
   North American implementation of this feature. (Subject to change)

     * Hello Direct 800 444.3556 (HIHELLO) or [phone]
     * ITS Communications, Endicott, NY 13760  800 333.0802 [phone]
     * Know Ideas Inc, [phone]
     * Lynx Automation, Inc., 2100 196th St SW #144, Lynnwood, WA 98036
       [phone].
     * Vive Synergies, 30 West Beaver Creek, Richmond Hill, ON Canada
       [phone]

   Costs for ring detection devices should be approximately USD $80 to 100.

   The March 1994 edition of Electronics Now magazine had a distinctive
   ring detector project, for those who wish to do it themselves. This
   project may need substantial modifications for use outside the U.S.
   and Canada, if customer-built attachments are permitted at all.

-------------
Miscellaneous
-------------

Q: Is there a way to find someone given just a phone number?

A: Sometimes. There are often cross-referenced city indexes available in
   libraries and other places that have lists ordered by the phone number.
   These directories go by names such as Bowers, Mights, Strongs or other
   brands. Unlisted numbers are not listed, nor are they intended to be
   traced by the general public. One catch is that such directories are
   necessarily out of date shortly after their publication what with the
   "churn" of changing telephone numbers and addresses. Still, these are
   at least annually updated, and are available at a price from the
   directory companies involved.

   In addition, there are phone numbers provided by telephone companies
   that connect to live lookup services. Operators at these numbers will
   determine a person according to the phone number. Only a few of these
   lookup numbers are intended for the general public (e.g. Chicago and
   Tampa). Some countries have also provided number to name lookup as a
   matter of normal telephone service, although these are often chargeable
   calls. Otherwise, most of these lookup numbers are for internal telephone
   company usage. Again, unlisted numbers are not intended to be provided
   by these services, while the listed numbers are often found in the
   introductory pages of local phone books.

   The Compuserve on line service had a facility (Phone File) to find
   names and addresses based on phone numbers. This facility is supposed
   to have more recent information for residential numbers than for
   business numbers. There are some concerns that the Phone File is not
   as accurate as it should be. Those interested should contact Compuserve
   staff for assistance or information on this service.

   Extra-charge numbers have been set up to provide reverse-directory
   services. Note that in some cases charges may apply even for
   unsuccessful searches:

   * UnDirectory is an automated, touch-tone-operated service within the
     U.S. (1 900 933.3330, $1 per minute, listing U.S. numbers)

   * Telename (sp?) is a live operator "900" service available within the
     U.S. during "business hours" (1 900 884.1212, give operator number,
     await lookup; $1.49 first minute, $0.75 per additional minute).

   * Chicago number lookups are available (312, 630, 708 areas) via
     [phone] (enter number on touch-tone; $0.35 for two lookups,
     long-distance charge only outside Chicago). This service is operated
     by Ameritech, the local exchange carrier in Chicago, thus this facility
     tends to have high accuracy.

   * There may be similar numbers in other regions that offer such lookup.
     If available, these would be listed in local directories.

   CD-ROM phone directories have been produced and are now available most
   places where software is sold. One of the more prominent producers of
   these is Pro CD, Inc, of Danvers, MA USA, makers of the SelectPhone and
   Canada Phone products. As such products are often typed in from annual
   telephone directories, the information in these CDs is subject to change
   or error.

   Telephone companies have Customer Name and Address (CNA) offices which
   provide number lookups. These are not intended for general public use.

   Private detectives seem to have other means of getting these numbers,
   but that's another story...

Q: Who are the Telephone Pioneers?

A: The Telephone Pioneers of America began almost a century ago, originally
   consisting of the 'charter employees' of the company, or 'pioneers' in
   telecommunications, mainly those who served with the Bell System at its
   outset. As time went on, there would be fewer living or active original
   Pioneers, thus the TPA charter was amended to allow membership by any
   employee of AT&T or (as they were called) a subsidiary company who had
   been employed by Bell (or an independent) for at least twenty years.
   Membership in the Pioneers was opened to more types of telephone company
   people over the years (including companies that are not "Bell" or AT&T).

   The Telephone Pioneers have a distinguished history of community service.
   Pioneers devise technical solutions to improve the lives of those with
   disabilities, allowing them to use telephones when this would otherwise
   be difficult or impossible. Pioneers also assist with general community
   activities such as voter registration, help those who are ill, feed those
   who are needy, and more.

   The Telephone Pioneers of America has chapters throughout the USA and
   Canada. At the non-Bell telcos, the same organisation is known as the
   Independent Pioneers.

Q: Where can a Cellular/Mobile Radio mailing list be contacted?

A: A mailing list dedicated to cellular/mobile radio technologies, namely
   new digital radio services, is available. Contact [e-mail].

   Fidonet has a CELLULAR conference for cellular telephony issues, for
   those with access to that network.

   The subject may appear in other Usenet newsgroups such as
   comp.dcom.telecom.tech.

Q: How are VCR+ codes generated?

A: This is not a telecom topic, considering that the VCR+ is a device
   used to program VCR machines for television viewing purposes. However,
   the makers of VCR+ operate a 900 chargeable phone line within the
   United States to allow citizens to obtain VCR+ coding information.

   The VCR+ coding is a 1 to 8 digit number that represents the channel,
   date, time and duration of a television program. These codes are
   found in many television listings and appear to have no relation
   with the time and channel that is represented.

   This coding method was intended to be rather secret and inscrutable,
   but this only served as a challenge to cryptologists. The coding
   system was cracked for up to 6 digit VCR+ codes; the details on
   the decoding were published in the journal Cryptologia many months
   ago. Programs are also available via FTP sites for VCR+ encoding
   and decoding.

   This topic is more appropriate for a newsgroup that deals with video
   or television.

Q: What is CLLI?

A: Common Language Location ID (CLLI) is a method of identifying locations
   and equipment. Bellcore developed the codings to allow the labelling
   of buildings, exchange offices, facilities (even poles, shacks, etc).

   Each full CLLI is eleven characters in length. Generally, the first
   four characters represent the place name such as a town or facility.
   The following two characters represents a state, province or other
   territory. The remaining characters identify the particular item
   within the place. In the case of switching equipment, these final
   characters might be formatted as two characters for the central
   office location, followed by other characters to identify the switch
   type, and machine within the building.

   A fictitious example, for Hill's Green, Ontario (HILL for town, ON
   for province/state code), with a telco building in Bean Sprout (BS)
   operating a remote switch (RS) could have a CLLI of HILLONBSRS0.

Q: Why do movies often use 555-xxxx numbers?

A: The use of a number that exists for an actual service can cause problems
   if listed in a movie or broadcast program. Audiences will attempt to dial
   the number out of curiosity.

   In the United States and Canada, 555-xxxx numbers are generally used for
   Directory Assistance (though a few exceptions exist for 800 and 900
   service, and occasionally for business services). Thus, phone companies
   will recommend 555-xxxx numbers other than the 555.1212 directory
   assistance number. Dialing such numbers usually results in a phone
   company recording or the directory assistance.

   Recently, 555 numbers have been assigned to various services. An example
   of this is the 555.1313 "Name That Number" facility introduced in some
   areas of Canada. There is supposedly a block of inactive 555 numbers that
   is still reserved for use in movies and television shows.

   Theoretically, 555 numbers could represent valid service numbers outside
   North America, especially for those countries having 7-digit local number
   formats.

Q: Are there cases of local calls across international borders?

A: Yes, mainly between Canada and the United States. There are several
   points along the New Brunswick (Canada) and Maine (U.S.) border that
   have cross-border local calling privileges. The known examples of
   Canada-U.S. border local calls are:

     Canadian side                   American side
     ---------------------------     ------------------------------
     Clair, New Brunswick        and Fort Kent and St Francis Maine
     Edmunston, New Brunswick    and Madawaska, Maine
     McAdam, New Brunswick       and Vanceboro, Maine
     St Leonard, New Brunswick   and Van Buren, Maine
     St Stephen, New Brunswick   and Calais, Maine
     St Regis, Quebec            and Fort Covington, New York
     Rainy River, Ontario        and Baudette, Minnesota
     Coutts, Alberta             and Sweetgrass, Montana

   Point Roberts in Washington state used to have local calling access to
   the Vancouver, British Columbia region on the Canadian side until that
   connection mysteriously disappeared and calls between those areas became
   long distance.

   No known U.S.-Mexico local calling arrangements exist.

   In other nations, "local" calling is often on a measured billing.
   Still, cross-border local or special-rate calling arrangements could
   theoretically occur.

   Technically, calls between the Vatican City and Rome could be
   considered a case of international local calling.

Q: Which countries have freephone or "800" services?

A: The "800" toll-free service in the United States and Canada is probably
   the first automatic freephone service. The service has become so popular
   that a new "888" code was assigned to provide capacity for more toll-free
   numbers. Previously, operator-handled services such as "Zenith" or
   "Enterprise" (or collect calling) were used to call companies at no
   charge to the caller.

   The UK uses 0800 (British Telecom) or 0500 (Mercury) for toll-free
   services. A 0345 code is used to complete calls at a local call rate.

   Switzerland uses numbers beginning with 155 for its freephone services.
   Numbers are of the form 155 xxxx. Outside Switzerland, these numbers
   can be reached (at international rates, NOT toll-free) by using
   +41 46 05xxxx (that is, area code 46, followed by 05 then the last
   four digits of the 155 number).

   Work is proceeding to establish an international "freephone" system
   using international dialing. 800 was recently established as a toll
   free country code to indicate the international freephone numbers.
   Progress on this matter will no doubt be reported in TELECOM Digest.

Q: How can one call 800 numbers from other countries?

A: Domestic toll-free services are intended for use within nations rather
   than for access from international points. However, many countries have
   set up agreements that allow for their domestic toll-free numbers to
   route calls to subscribers in other nations. Thus a UK 0800 number could
   reach a point in the U.S. or Canada. Such arrangements are normally
   reciprocal, thus North American 800 numbers can also be arranged to
   reach UK points.

   Recent reports from the UK indicate that North American 800 numbers
   can also be reached with the use of international dialing. These calls
   are NOT toll-free but are charged at conventional international rates.
   The purpose of this arrangement is to allow access to North American 800
   numbers.

   AT&T's USA Direct Service allows calls to North American 800 numbers
   from other countries, providing USA Direct service is available. The
   restriction that only AT&T's 800 numbers could be reached is no longer
   in effect. However, the 800 number must be reachable from the U.S. city
   at which the USA Direct call is handled. An AT&T Calling Card is also
   required, and there will be international charges to reach the U.S.
   from other nations.

   Other home direct services may allow for the possibility of 800 number
   access. Individual carriers will determine whether such service is
   available and at what cost.

   Some Canadian long distance carriers have a feature that allows calls
   to U.S. 800 numbers that are not otherwise reachable from Canadian
   networks. Charges for such 800 bypass are often CAD$0.10 per minute.

Q: Which World-Wide Web (WWW) sites have telecom information?

A: There are plenty of telecom-related web sites available, especially
   in the past year or two. More of these will be announced in TELECOM
   Digest (comp.dcom.telecom) as they are made available.

   One could check index sites such as Yahoo (http://www.yahoo.com) or
   Lycos for telecom-related listings. Telecom companies, equipment
   manufacturers, regulatory agencies and more are accessible.
   Such listings are updated over time.

   Note that any addresses listed here are subject to change. Those
   listed are definitely not the only ones available; there should
   be enough listed here as starting points in the grand tradition
   of net surfing.

   One major index of telecom-related websites is at:
       http://www.spp.umich.edu/telecom/telecom-info.htm

   Teleglobe also maintains a telecom links index:
       http://www.teleglobe.ca/~leo/teleurl.html

   Government/Regulatory/Standards bodies:

       http://www.itu.ch/                           ITU (int'l standards)
       http://www.fcc.gov/                          FCC (USA regulator)
       http://www.crtc.gc.ca/                       CRTC (Canadian regulator)

   National Companies/Consortiums:

       http://www.inmarsat.org/                     Inmarsat (satellite)
       http://www.stentor.ca/                       Stentor (Canadian telcos)
       http://www.ntt.jp/                           NTT (Japan)
       http://www.singtel.com/                      Singapore Telecom
       http://www.telkom.co.za/                     Telkom (South Africa)
       http://www.vptt.ch/                          PTT (Switzerland)
       http://www.bt.net/                           BT (UK)

   Other Pages (personal or otherwise off the beaten path):

       http://www.angustel.ca/                      Angus (Telecom Update)
       http://www.io.org/~kawchuk/                  HALT, other goodies
       http://www.castle.net/~kobrien/telecom.html  another telecom page
       http://www.io.org/~djcl/phoneb.html          assorted items


Q: What's an ObTelecom?

A: ObTelecom, or Obligatory Telecom Content, is used whenever a Digest
   article appears to be off-topic. But the ObTelecom banner assures
   everyone that it really has *something* to do with telecom after
   all. Or so one should think.

Q: Who contributed to this FAQ?

A: The initial edition of the FAQ was dated 28 August 1991.

   Thanks to Nathan Glasser, Dan Boehlke and Maurice E. DeVidts and those
   other inquiring TELECOM Digest minds for their frequent questions in
   the early versions.

   For v.3, the following people contributed comments, extra questions
   and other updated information:

   Alan Barclay, ([e-mail])
   Steve Beaty ([e-mail])
   Rick Broadhead ([e-mail])
   Gordon L. Burditt (sneaky.lonestar.org!gordon)
   Tad Cook ([e-mail] or [e-mail])
   David G. Cantor ([e-mail])
   Tony Harminc ([e-mail])
   Carl Moore ([e-mail])
   Gary Morris ([e-mail])
   Dan Sahlin ([e-mail])

   For v.4 the following people contributed more comments and information
   (sometimes adapted from the regular Digest postings):

   Mark Brader, Richard D G Cox, Brad Hicks, Dave Levenson, Don McKillican,
   Jim Morton, Colum Mylod, Peter Sint, Pat Turner and Al Varney

   For v.5 (1994) the following people are the source of even more
   comments and information whether direct or indirect:

   Jack Decker
   J. Delancy ([e-mail])
   Adam M Gaffin ([e-mail])
   Fred R. Goldstein ([e-mail])
   Rich Greenberg ([e-mail])
   Emilio Grimaldo ([e-mail])
   J. Brad Hicks (mc![e-mail])
   Chris Labatt-Simon ([e-mail])
   Fernando A. Lagrana ([e-mail])
   Andy La Varre ([e-mail])
   Marty Lawlor ([e-mail])
   Greg Monti ([e-mail])
   Carl Moore ([e-mail])
   John Paul Morrison ([e-mail])
   Hans Mulder ([e-mail])
   Lars Poulsen ([e-mail])
   Paul Renault ([e-mail])
   Robert Shaw ([e-mail])
   Andy Sherman ([e-mail])
   Bill Sohl ([e-mail])
   Bruce Sullivan ([e-mail])
   A Alan Toscano ([e-mail])
   Pat Turner KB4GRZ
   vantek ([e-mail])
   Victor R. Volkman ([e-mail])

   For v.6 (1995) the following people are the source of still even more
   comments and information whether direct or indirect:

   Nigel Allen ([e-mail])
   Marc Baime ([e-mail])
   Michael Bloch ([e-mail])
   Tad Cook ([e-mail] or [e-mail])
   Jim Gottlieb ([e-mail])
   Kimmo Ketolainen ([e-mail])
   Jonathan ([e-mail])
   Wes Leatherock ([e-mail])
   Carl Moore ([e-mail])
   Blake R Patterson ([e-mail])
   Jonathan Prince ([e-mail])
   Anthony Sylvester ([e-mail])
   Eric Tholome ([e-mail])
   Charles A. Tievsky ([e-mail])
   Patrick Townson ([e-mail])

   For v.7 (1995) the following people are the source of still even more
   comments and information whether direct or indirect:

   Mark Brader ([e-mail])
   Stan Brown ([e-mail])
   John N. Dreystadt ([e-mail])
   Pat Duignan ([e-mail])
   John R. Grout ([e-mail])
   Stu Jeffery ([e-mail])
   John ([e-mail])
   Martin D Kealey ([e-mail])
   Basavaraj Patil ([e-mail])
   Rajgopal Rayru ([e-mail])
   Les Reeves ([e-mail])
   Steve Summit ([e-mail])

( end of list )

                         ---------

Send future Frequently Asked Questions direct to the addresses mentioned
at the beginning of this document. Do NOT use any of the TELECOM Digest
addresses for correspondence regarding the FAQ unless all the other FAQ
addresses are unreachable.