VOIP Glossary of Terms Page 1 Attended Transfer Transfer an existing call to another telephone number after first consulting with the dialed party before the user hangs up. Auto Attendant Automated receptionist. Calls made to specific number cause a greeting to be played asking for the extension number of the person they wish to reach. The call will be transferred to the extension number entered. Bandwidth Bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps). B2BUA Back-to-Back User Agent. SIP based logical entity that can receive and process INVITE messages as a SIP User Agent Server (UAS). It also acts as a SIP User Agent Client (UAC) that determines how the request should be answered and how to initiate outbound calls.Unlike a SIP proxy server, the B2BUA maintains complete call state and participates in all call requests. Busy Call Forwarding When dialed party's line is busy, the call is automatically transferred to a predetermined number. Call hold Place a call on hold temporarily while you place a second call or answer another call. Call Hunting Delivers the incoming call to the next available station or group when the called station in the group is unanswered. Call Detail Record (CDR) Information regarding a single call collected from the switch and available as an automatically generated downloadable report for a requested time period. The report contains information on the number of calls, call duration, call origination and destination, and billed amount. Call duration The time interval between when the phone is taken off the hook and when it is put back on the hook. Call setup time The length of time, measured in seconds, required to establish a call between users. Carrier A long distance company which uses primarily its own transmission facilities, as opposed to resellers which lease or buy most or all transmission facilities from carriers. Many people refer to any type of long distance company, whether it has its own network or not, as a carrier, so the term is not as restrictive as it used to be. Circuit-Switched A type of network in which a physical path is obtained for and dedicated to a single connection between two end-points in the network for the duration of the connection. Ordinary voice phone service is circuit-switched. The telephone company reserves a specific physical path to the number you are calling for the duration of your call. During that time, no one else can use the physical lines involved. Class 4 AT&T's name for the type of switch used in a telephone tandem office. In the past, Class 4 switches dealt only with high-speed, four-wire T1, T3 and OC-3 connections in contrast to two-wire local lines on Class 5 switches. Today, all switches support four-wire lines. Class 5 AT&T's name for the type of switch used in a local telephone end office. It provides customer services such as call waiting and call forwarding. In the past, a Class 5 switch implied two-wire ports from the customer and four-wire ports out the back end. Today, all switches support four-wire lines. Codec Voice encoding/decoding mechanism. Codecs are used to compress the voice signal into data packets. Each codec has different bandwidth requirements. The most popular codecs are: G.729, G.729A, G.723.1, G711A-Law, and G.711mU-Law. Competitive Local Exchange Carrier (CLEC) A U.S. telephone company that competes with the already established local telephone business by providing its own network and switching. The term distinguishes new or potential competitors from established local exchange carriers (LEC) that were providing local service when the Telecommunications Act of 1996 was enacted. Conference Bridge A device used to connect multiple parties over the phone. A proctor or operator can man conference bridges, or the can be supervised. There are both stand-alone conference bridges and conference bridge functions built in to some PBXs (Private Branch Exchange). These systems have circuitry for summing and balancing the energy (noise) on each channel so everyone can hear each other. More sophisticated conference bridges have the ability to "idle" the transmit side of channels of non-speaking parties. Some conference bridges use "clVoxising" to idle or reject the input of touch tones or other signals. CTI Computer Telephony Integration. Telephone systems utilizing computer technology. DID Direct Inward Dialing The ability to make a telephone call directly into an internal extension without having to go through the operator. DNIS Dialed Number Identification Service A telephone function that sends the dialed telephone number to the answering service. DTMF (Dual-tone multifrequency) The system used by touch-tone telephones. DTMF assigns a specific frequency (made up of two separate tones) to each key so that it can easily be identified by a microprocessor. This is basically the technology behind touch tone dialing   Next