ANI (Automatic Number Identification)
15 May 2006
A telephone function which transmits the billing number of the incoming call (Caller ID, for example).
ARU (Audio Response Unit)
15 May 2006
A computer telephony system incorporating voice store and forward technology. There are both passive and interactive ARUs. Passive ARUs simply play out messages. Interactive ones play messages based on input from callers.
Asynchronous Communication
15 May 2006
A data communications method in which bits are sent one after the other with a start and stop bit used for flow control. This as opposed to synchronous communication where blocks of data are transmitted using a synchronizing clock.
ATA (Analogue Telephone Adapter)
15 May 2006
The ATA is an analog-to-digital converter. It is a device that allows you to connect a standard phone to your Internet connection for use with a VoIP service. The telephone adapter converts voice signals from your telephone into the digital "IP" format required for transmission over your broadband connection. The adapter is connected to your DSL or cable modem, your PC or router, and to any digital phone.
Audio Teleconferencing
15 May 2006
Or Audio Conferencing. The original technology used for audio teleconferencing was based on PBX conferencing circuits. Setting up conference calls through the PBX is cumbersome, voice quality degrades as the number of people on a call increases and there are capacity limitations. As a result, specialized conference bridges were developed to improve capacity and voice quality. Conference bridges, however, require trained operator intervention to schedule and invoke most features. As a result, individual corporations find the cost of ownership prohibitive, and the market for such products has been concentrated on service bureau providers. Today, PC-based systems combine the freedom of conference bridges. By installing a conference server on your voice networks, you can set up, attend, and manage your own conferences over any touch-tone telephone. Additionally, users can schedule meetings using desktop software from their e-mail systems, or from a Web browser.
Backbone
15 May 2006
A high-speed network spanning the world from one major metropolitan area to another.
Conference Bridge
15 May 2006
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.
DID (Direct Inward Dialing Number)
28 May 2006
Also called DDI in Europe. This is a feature which is offered by telephone companies to use with their customers' PBX. If you know a person's DID, when you dial this number, you will be connected directly to this person's phone, bypassing the switchboard. This essentially makes it possible for companies to have a limited number of physical lines e.g. 3 lines but many extensions e.g. 10 extensions.
In order to be able to make calls from traditional PSTN to VoIP, these DID has to be assigned to a gateway in the VoIP network. The gateway will then route calls incoming from the PSTN across the IP network to the appropriate VoIP user. Similarly, calls originating in the VoIP network will appear to users on the PSTN as originating from one of the assigned DID numbers.
DiffServ (Differentiated Services)
28 May 2006
A quality of service (QOS) protocol that prioritizes IP voice and data traffic to help preserve voice quality, even when network traffic is heavy.
DNIS (Dialed Number Identification Service)
28 May 2006
A telephone function which sends the dialed telephone number to the answering service.