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- The LOD/H Technical Journal, Issue #3: File 05 of 11
-
- *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
- (L) (L)
- (O) An Overview of the Teradyne 4Tel System (O)
- (D) (D)
- (+) by (+)
- (+) (+)
- (+) Doom Prophet (+)
- (L) (L)
- (O) Legion of Doom/Hackers! (O)
- (H) (H)
- *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
-
-
- 4TEL is a loop testing system mainly used by General Telephone (GTE) that
- consists of a Voice Response System and a Craft Dispatch Section as well as
- the facilities and equipment used for testing functions. The following text
- will attempt to dispell many of the 4TEL myths that have been created in the
- past years, such as the idea that it can be used to eavesdrop on lines within
- its serving area. The information provided has been gained from company
- publications and from personal experience. A 4TEL is not the same thing as a
- REMOBS, which stands for REmote service OBservation System.
-
-
- The portion of the system that some of the phreak/hack population is
- familiar with is the Voice Response System, which has normal POTS dialups.
- This system greets the user with an announcement message and then asks for a
- password, which is entered in DTMF tones. The legitimate use of these dialups
- are for outside craft personnel (linemen) to call in, perform tests and
- receive the results for subscribers' lines. The VRS is provided so craft
- personnel can access the 4TEL system at times when no one is at the testboard
- (at nights or weekends). Through the VRS, up to 8 craft/technicians can access
- 4TEL at the same time, enabling them to get more done in a smaller amount of
- time.
-
-
- After a password has been accepted by the system, the electronic voice
- will ask for the line number that the user wishes to be tested. The number
- entered will be read back to ensure correct entry. The system will then ask
- for the user to enter the mode. The modes are:
-
-
- 1: Calling on other line
- 2: Calling on test line
- 3: Line test results
-
-
- It is possible on some VRS's to get a listing of the modes by dialing 0
- when the voice prompts. Line tests are possible from both modes 1 and 2 by
- dialing the octothorpe (#) key. The results of the test will be announced
- along with the length of the cable in miles. Bridged ringers, if any, will
- also be noted. Mode 3, the line test results section, will tell the user there
- are no test results available unless they have beeen previously entered. The 7
- key is the monitor command from both test modes. If there is speech on the
- line, it will be detected electronically but will NOT be heard by the user.
- The monitor command is not 'REMOBS' (Remote Observation) but a method of
- determining if the line is busy due to normal means (conversation) or due to
- some trouble condition at the switch. When the system asks for the ID code for
- a monitor command, the system will accept the line number as well as the
- initial password, and even a secondary password before dialing, but it has not
- been determined by the author if this is a standard for every 4TEL. Not just
- anything will work for the monitor password however as it will announce if the
- ID code entered is invalid or not.
-
-
- If mode 1 is entered, these commands are available:
-
-
- MODE ONE COMMANDS:
-
-
- 1-Fault location
- 2-Other Testing
- 7-Test OK, monitor
- 8-Hang up
- 9-Enter next line number
-
-
- If option 7 is chosen, another menu will be available if the line tests
- busy.
-
-
- 2-Monitor test
- 3-Overide and test
- 4-Wait for idle
-
-
- If suboption one (Fault location), mode one, is chosen, these commands are
- available:
-
-
- 1-Open location
- 3-Short location
- 4-Cross location
- 5-Ground location
- 8-Hang up
-
-
- If suboption two (Other testing), mode one, is chosen, these commands are
- available:
-
-
- 2-Loop ground Ohms
- 3-Dial tone test
- 4-Pair ID
- 8-Hang up
-
-
- MODE TWO COMMANDS:
-
-
- 2-Other testing
- 7-Test OK, monitor
- 8-Hang up
- 9-Enter next line number
-
-
- If suboption 2 (Other testing), mode two, is selected, these commands are
- available:
-
-
- 2-Loop ground Ohms
- 8-Hang up
-
-
- The 4TEL system's main use is for standard testing, which is done nightly
- upon every line in an exchange. This locates faults and problems before they
- have to be reported by customers. All lines that have trouble detected upon
- them are printed out in a report at the repair center the next morning where
- the proper fault location and dispatching can be done. The measurement and
- test unit of the 4TEL system is called a COLT, Central Office Line Tester,
- which performs all nightly and on demand testsupon the exchange through local
- test trunks.
-
-
- There are a few different types of COLTs. The standard version will serve
- any CO for up to 10,000 subscribers. The COLT RS is used in rural step by step
- offices (referred to as 'steppers' also) for up to 1,300 lines. The Digital
- COLT is used for digital Central Offices. These can have remote Colt
- Measurement Units (CMU's) for remote switches which are controlled by the Colt
- Computer Unit (CCU) at the host switch. The CMU speed calls the CCU at night
- to start the testing and direct the operations. The CMUs in regular end
- offices have digital links (over the normal telephone network) with the SAC,
- which is how the line test results are distributed to the repair center.
-
-
- The 4TEL system can also test lines upon command by a human operator at
- the SAC (Service Area Computer). The CRT operator enters the line number in
- the proper field and 4TEL runs a full series of tests as well as displaying
- past line history, fault summary, volts and current information, and the cable
- length. The results of the testing are displayed in plain english, as opposed
- to decimal or other format, on the screen. A dispatch decision is also
- displayed after every line test to determine if a dispatch is needed.
-
-
- SAC's
- -----
-
-
- The SAC is the centralized focal point for 4TEL control and reporting.
- This computer is located in the repair center and distributes test/work
- information between CRT's and COLT's. The SAC formats the results of routine
- testing into a daily advisory report as mentioned earlier.
-
-
- There are several types of 4TEL reports that are worth noting. The
- DISPATCH report lists troubles that can have an immediate dispatch for them.
- These also tell the location of the fault (cable, CO, station, etc.) and are
- classified into two types, moderate and severe, relating to how service
- affecting the problem may be. The CABLE report lists all new cable faults. A
- Plant Status report summarizes the condition of the outside plant and totals
- them per individual exchange. In these reports, trouble conditions can be
- listed in a variety of ways. CROSSES and WETS refer to line insulation faults
- and may indicate water penetration of the cable. SHORTS and GROUNDS are
- insulation faults at the station set. OPENS refer to a broken, or 'open' Ring
- or Tip lead in a Cable Pair. BACKGROUND refers to electrical noise caused by
- power lines being nearby. ABNORMAL VOLTAGE indicates high voltage conditions.
- There are others, but the reader will hopefully get the idea from the ones
- listed above.
-
-
- CDS
- ---
-
-
- Another major part of the 4TEL system is the Craft Dispatch System, which
- is a DTMF and speech response setup used to exchange report and schedule
- information between the repair center staff and outside craftspersons. Linemen
- call in to get dispatch information that has been previously entered by the
- dispatcher. CDS plays back the info one field at a time. When the craft
- personnel is ready to receive the next field of information, he simply says
- 'Go' and the system continues. A printer at the repair center informs the
- dispatcher when a craftsperson has received a report. When the trouble is
- taken care of, a completion report is done on the CDS in which it asks for the
- closeout and schedule one field at a time to be entered in DTMF and in speech.
- The clerk at the repair center then closes the trouble on the SAC/4TEL system
- after the line is tested a final time to ensure proper operation.
-
-
- CDS may also have audit trails of every transaction for a certain time
- period. So to summarize the work flow for involving the CDS: Irate customer
- calls the clerk at the repair center. The information is forwarded to the
- dispatcher who enters it into CDS. Craft personnel call in and receive the
- messages, do the required work, then file a completion report. The clerk then
- closes out the trouble in SAC/4TEL.
-
-
- The Digital Concentrator Measurement Unit is another component of the 4TEL
- testing equipment that is used to test lines in digital concentrators such as
- the GTE MXU and the NTI-OPM. They are located inside Digital Loop Carrier
- system remote terminals or huts and consist of a circuit board and measuring
- system. It provides AC and DC measurements of subscriber loops, as well as all
- the normal test/measurement functions such as fault description and location ,
- dispatch messages, and special tests. The DCMU can test the lines of an
- individual DLC remote terminal, or a group of terminals that are located
- together. The capacity of terminals that the DCMU can test is determined by
- analysis of test traffic and economic factors as well. Both the CRT at the SAC
- and the VRS are compatible with the DCMU. These units are self calibrating,
- unlike the PMU's of an LMOS supported Loop Testing System. The 4TEL CCU is
- linked to the DCMU via either a 1200 baud dial up or a dedicated link,
- depending upon the size of the office.
-
-
- Some of the tests that 4TEL performs are loop and ground resistance (which
- detects resistance faults and sheath ground problems), dial tone test (in
- which the number of times dial tone can be drawn during a certain period is
- recorded) , busy line monitoring (not BLV or REMOBS), coin station tests
- (totalizer, coin relay, etc), as well as all the standard tests which were
- covered above. A pair identification can also be done, in which a tone is
- placed on the pair to help those at terminal cabinets locate that specific
- one, similar to the LMOS/MLT tone applique function.
-
-
- Miscellaneous notes
- -------------------
-
-
- If a user enters the number of the 4TEL system they have dialed in upon,
- the system will announce an intercept. A user cannot monitor/test Directory
- Assistance through 4TEL. Lines that are out of the system's NPA can be tested
- also, but a 1 has to be dialed before the number just like an ordinary toll
- call. The 4TEL VRS will give the user a 'beep' tone after a few seconds of
- waiting for input. If the user doesn't enter anything, the VRS will
- disconnect. A version of 4TEL is also used by Rochester Telephone in New
- York, and there may be other independent companies that use the system. Try
- to find out what system you're served by. If you're in a Bell area, it will
- most likely not be 4TEL, but LMOS.
-
-
- I hope that this article has helped readers to better understand the way the
- 4TEL system operates. Again, there may be some differences depending upon the
- area and the company. Thanks go to Taran King, Phantom Phreaker, and Lucifer
- 666 for supplying information in one way or another that contributed to this
- file.
-
-
- Doom Prophet/LOD
-