guide to telephone terminology 103
A2 Telephone Terminology Guide
You’ll get better results from the Telco if you understand and speak the lingo! We have tried to include the typical acronyms used by Telco personnel. We’ve put the definition under the most commonly used acronyms.
AMI – Alternate Mark Inversion. A T1 line coding method. This is the older of the two commonly available. Modified AMI is also used on the ISDN S interace. See line coding, T1. See Also B8ZS.
ANI – Automatic Number Identification- A system, originally de- signed for use by Interexchange carriers (IECs), that transmits the “billed party number” along with a call. Note that the billed party number is not necessarily the number of the line placing the call. ANI predates SS7 and can operate with analog as well as digital trunks. See also CLID and Caller ID.
Asynchronous Data - A form of serial data communication that is not clocked. To keep the bit stream synchronized, start and stop bits are added, which cuts down on throughput.
Acoustic Echo Canceller (AEC)- When an acoustic path exists from a microphone to a loudspeaker in a teleconferencing applica- tion, the
B Channel - Bearer Channel. One of the multiple user channels on an ISDN circuit. Used to carry user’s data; i.e. coded audio data in the case of Zephyr or ZephyrExpress.
B8ZS- Bipolar 8 (with) Zero Substitution. A T1 line coding method. This is the more modern line coding method of the two commonly available. See Line Coding, T1. See also AMI
Bearer Channel- See B Channel
Behind the PBX- This is our own term, and refers to when one privately owned phone system is tied to another privately owned phone system. The most common application is when a key system is connected to analog ports of a PBX. When it involves one PBX behind another, it is a limited Tandem application. See Tandem Switch and Tandem Tie Trunk Switching below.
Bell Labs. The basic research facility that was AT&T’s primary research facility. Bell Labs was originally part of Western Electric and was spun off with Lucent Technologies when AT&T was broken up in 1984. Many very important discoveries were made at Bell Labs including the transistor, communications theory, and radio astronomy. The future of Bell Labs seems bleak at the time of this writing.
Bell Operating Company. See BOC. See also RBOC.
Bellcore- BELL COmmunications REsearch. See Telcordia. The research and development organization owned by the RBOCs. Bellcore represents the RBOCs in developing standards for Telco equipment and in testing equipment compliance to those standards. Bellcore also offers educational and training programs open to all interested parties. Now Telcordia.
BERT - 1) Bit Error Rate Test- A test for digital lines which in- volves looping a data path and sending a test pattern. Data return- ing is compared to the sent data to check for errors. Depending on the “Test Pattern” used, BERTs may or may not uncover problems. A line, which only has occasional problems, will need a BERT of sufficient time duration to catch that intermittent problem. A five minute BERT of an ISDN BRI circuit will only catch severe prob- lems. 2) Bit Error Rate Tester. The test equipment used to perform a Bit Error Rate Test.
Billing Telephone Number- The main phone number which all calls on hunt group or a PRI are billed to. This information may be required when configuring a PRI PBX.
Bit Error Rate- The basic measure of errors on digital transmission paths. It is usually expressed as the number of errors per number of bits. For example, the allowable bit error rate on a BRI circuit is 1 x 10 E7 (one bit error in 107 bits or 1 error in 10 million bits).
Bit Error Rate Test-See BERT
Bit Rate- The capacity of a digital channel. ISDN calls are set up at a given bit rate, either 64Kbps or 56Kbps. The bit rate of a circuit- switched connection cannot be changed during a call. See Kbps.
BLEC- Building Local Exchange Carrier. A LEC who covers the occupants of a single building (or a small group of buildings) only. Often Telecom services are provided by a BLEC as a service
