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  Downloaded From P-80 International Information Systems 304-744-2253 12yrs+