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- \ /
- / R O U T I N G A N D S Y S T E M C O D E S \
- \ /
- / Part I \
- \ /
- / By The Doctor (Who) \
- \ in Rockville, Mayland /
- / 7/10/85 \
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- 1. Introduction
-
- The Bell system, as it is today, offers a wealth of opportunities for
- phreaks. However, Bell doesn't like us to have access to these niffties, so
- they hide many special services in that vast block of non-standard numbers
- which a customer cannot normally dial.
-
- Thats what this tutorial is all about, the non-standard numbers which
- Bell hides from us. We'll take a look first at the Network structure, then the
- numbering plan for North America, then at Routing and System codes, including
- operaters, test lines, OUTWATS, international calling, and more.
-
-
-
- 2. Structure of the Network
-
- The Bell system is organized as a hierarchal network with 5 levels.
- The lowest level, or class 5 office, is the End-Office (EO from here on).The
- EO is also called the central exchange, wire center, or central office.This is
- where all the subscriber lines are connected for a given exchange number.Each
- EO can handle at least 10,000 lines; #5 ESS can handle upto 100,000.Calls
- between subscribers in the same EO are connected internally and never leave
- the building whereas calls between subscribers in different EO's travel over
- inter-exchange trunk lines.Calls that never go higher than the class 5 office
- or Tandem office (hold on, I'm getting to it) are local and therefore free.
-
- In large NPA's that have many EO's, it is uneconomical for each EO
- to have at least 12 trunks (the minimum laid at a time) to every other EO.
- Imagine,in a city with 600 EO's, there would be 17970 inter-office trunk
- cables to maintain! There simply aren't that many simultaneous conversations
- going on at any given time, so many trunks would be unused. Instead, Bell has
- adopted an intermediate switching level called the Tandem Office. A tandem
- Office is to the EO's as a EO is to its subscribers. Local traffic between 2
- EO's which don't have direct connecting trunk lines passes through the Tandem
- office. Under this scheme, a city of 600 EO's would only require 600 inter-
- office trunk cables, that is quite a reduction!
-
- Subscribers in different NPA's (Numbering Plan Areas, or area codes)
- are connected through the Toll Network. The first level in the Toll Network is
- the class 4 office, or Toll Center (TC from here on). Each exchange has
- dedicated trunks that connect it to the TC that serves it, so a cable map would
- look like a star with all the exchanges having a cable to a central point.Once
- a call has reached the TC, it does one of four things:
-
- 1. It immediately leaves the TC for the called exchange.This ussually
- is the case if the parties are served by the same TC but are not
- local to each other.
-
- 2. It leaves the first TC over trunks in the High-Usage-Trunk-Group
- for the TC serving the called party where it then reaches the
- called exchange.This is the case during non-peak hours.
-
- 3. It leaves the TC over trunks in the Final-Trunk-Group for the
- primary center (to be discussed in a moment).This route is followed
- when all the High-Usage-Trunks are busy.
-
- 4. If none of the above choices were taken, then all the trunks are
- busy. The calling line either gets a re-order tone (fast busy), or
- a recording saying all circuits are busy.
-
- After the TC,there are three higher levels that function in exactly
- the same way.Each level can connect to any other level.As you can see, a call
- can climb a "communications ladder", going from Toll Center to primary center
- to sectional center to regional center and back down again to reach the called
- party.In order, the overall structure of the Network is:
-
- class 5 office - End office or Exchange
- class 4 office - Toll Center 508 as of 1983
- class 3 office - Primary center 148 as of 1983
- class 2 office - Sectional center 52 as of 1983
- class 1 office - Regional center 10 as of 1983
-
-
-
- 3. Numbering Plan of North America
-
- When Bell introduced Direct Distance Dialing (DDD) in the 1960's, they
- set a standard for telephone numbers. Any subscriber anywhere in the United
- States can reach any other subscriber by dialing a 10 or 11 digit " Network
- Address." The format for a standard (that is, customer dialable) number is a
- three digit area code followed by a 3 digit End-office code followed by a 4
- digit station number. In some areas, it is necessary to dial a preceding 1 to
- identify the call as long distance.Symbolically,numbers can be represented by:
-
- X - Any digit 0 to 9
- N - any digit 2 to 9
- Z - 0 or 1
-
- area code - NZX
- exchange - usually NNX, but some are NZX (like an area code in appearance)
- station - XXXX
-
- Bell also defined 200 special codes in each area code that a customer
- cannot normally dial.These codes perform system functions, request operaters,
- an influence the route a call takes.In addition, each Toll Center has a routing
- code that lets you force the call to pass through it (more on this later).They
- are in the format of:
-
- Special codes- ZXX (all routing and system codes are in this format)
- operaters - 1X1 (such as 101,121,131,141,191,etc)
- Toll centers - 0XX
-
-
-
- 4. Operaters, routing codes, OutWats, and International calling
-
- Many special operaters exist in the Bell system.Some of them, like
- CN/A operaters, have standard, customer dialable numbers. However, many others
- can only be reached via the appropriate routing/system code.These are......
- (an optional area code can be put in front of them.i.e. KP+301+121+ST to get
- an inward for Maryland):
-
- 101 - Toll Center test board (Toll maintainance personnel). These people
- are great for social engineering because they almost never get
- suspicious calls from phreaks.I think they can perform traces of
- customers lines for you.
-
- 121 - Inward operater. This operater assists the Toll and assistance
- ("0") operater in making emergency interruptions to numbers in
- other area codes.They can also complete a normal call or, if you
- ask them for "loop around" numbers, they will give you the numbers
- of working loops.To get an emergency interruption, say:
- "I need an emergency interruption on 301-555-1212.My party's name
- is Bill Smith."
-
- 131 - Directory assistance for Toll and Assistance operaters. This is
- just a supped up version of the 555-1212 directory assistance
- operater.The only difference that I know of is that they can do
- emergency interruptions.
-
- 141 - Rate & Route operater. Reach at 800-141-1212.
- To find out... (quoted from Bioc's Basic Telecommunications VII)
- 1)Area codes
- say: "Miami,Florida (any city), numbers route please."
- response: "305 plus" (meaning 305 is the area code)
- 2)Inward operater numbers (usually 121, but can have a prefix)
- say: "916-756 (any NPA-EXG), operater route please"
- response: "916 plus 001 plus" (meaning 916-001-121)
- 3)City names
- say: "Place name,301-340 (any NPA-EXG),please"
- response: "Rockville, Maryland"
- 4)International Directory Assistance numbers
- say: "International,London,England (any city), TSPS
- directory route,please"
- response: "Directory to London,England.Country code 44 plus 1
- plus 986 plus 3611"
- 5)Country and City codes
- say: "International,Sydney,Australia (any city), TSPS
- numbers route,please."
- response: "Country code 61 plus 2"
- 6)International inward operaters
- say: "International,London,England (any city),TSPS inward
- route, please."
- response: "Country code 44 plus 121"
- 7)Language Assistance operaters (use with foriegn inward,not R&R)
- say: "United States calling. Language assistance in
- completing a call to <called person's name> at
- <person's number>."
-
- 151 - Overseas incoming (NPA 212 and 914)
-
- 161 - Trouble reporting operater. Reach at 800-161-1212
-
- The following operaters only exist in certain area codes (212 for example):
-
- 11501 - Universal cordboard operater
- 11511 - TSPS conference operater (not the same as an Alliance operater)
- 11521 - Mobile operater
- 11531 - Marine operater
- 11541 - Long Distance incoming switchboard
- 11551 - Leave word for time and charges
- 11561 - Sames as above but for Hotels/Motels
- 11571 - Overseas operater.Language assistance.
-
- The Bell system also hides many test and routing numbers from it's
- customers in the ZXX series.A few of them are listed below.
-
- 001 - Trunk access system.Usually used as a prefix before another code.
- 009 - Rate quote system. Gives the toll and assistance operater rate
- information.Although I don't know the command format, I know it
- accepts MF for control.Most area codes have this system function,
- but 713 does for sure.
- 011 - prefix for international calling
- 080 - Alliance Teleconferencing Toll Center code in many areas.(213)
- 100 - loop, tone side
- 103 - loop, dead side
- 105 - verification (Long-Short beep)
- 191 - International operater in some areas,911 emergency system in others
- 11601 - another inward in some areas (212)
- 11611 - Computer that checks Calling Cards in 212. After the bong, enter
- the calling card number in DTMF and if it's valid you will get a
- message saying so.
-
- As mentioned previously, each Toll Center in the network has a 3 digit
- code in the form of 0XX. This is used primarily when dealing with area codes
- that cover more than 1 major city. For example, Alaska has just the 907 area
- code, but more than 1 major city. To reach an inward or Toll Center test board
- for the appropriate city, you have to enter the Toll Center code for that city.
- Otherwise, the switching equipement won't know which of the major cities is
- wanted. KP+907+101+ST won't work, you have to dial KP+907+054+101+ST if you
- want to reach the Test board in Ankorage. The 054 code forces the call to
- go through the Toll Center there.
-
- International dialing in the Bell system is accomplished by calling up
- one of the 7 international senders and then dialing the international number.
- The sender codes and their locations are:
-
- 182 - White Plains, New York
- 183 - New York, New York
- 184 - Pittsburg, Pensylvania
- 185 - Orlando, Florida
- 186 - Oakland, California
- 187 - Denver, Colorado
- 188 - New York, New York (again)
-
- There are two ways to get to a sender.The simplest way is to dial
- KP+sender code+ST (i.e. KP+188+ST). A prefix area code is sometimes required
- (i.e. KP+213+188+ST).Another way which arouses less suspicion, is to use the
- 011 international dialing prefix.To use it, dial KP+011+0+country code+ST
- i.e. KP+011+081+ST for Japan). Again, a prefix area code is often
-