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. This is the feature of OnDO PBX.   



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.  



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.



Direct Inward Dialing
Allows incoming calls from PSTN to PBX to reach a specific PBX extension without human intervention.  



Gateway
A gateway is basically a protocol converter, i.e. a network point that connects networks using different protocols so that data can be exchanged seamlessly between endpoints. For example, a POTS-to-VoIP Gateway connects PSTN and packet-switched networks, translating the media into IP packets, so that "legacy" telephony becomes Voice-over-IP.  



H.323
An ITU-T (International Telecommunications Union's Telecommunications sector) standard for handling video, data, and voice call information.  



IP
Internet Protocol
One of a large family of specifications that define the transmission of information over data networks. It tracks the Internet addresses of nodes, routes outgoing messages, and recognizes incoming messages.  



IP-PBX
A system that allows voice communications over a TCP/IP network, and adds new functions to the current generation of PBX technology. Both hardware and software IP-PBXfs are available. For more information, please see the PBX entry below.  



IVR
Interactive Voice Response
Technology in which a human caller can interact directly with a database without operator assistance. An airline, for example, might offer up-to-date flight information using an IVR system.  



MGCP
Media Gateway Control Protocol
According to IETF (RFC 2705), MGCP is a standard for converting voice signals sent over PSTN to data packets that can be sent over the internet. MGCP


  
PBX
Private Branch Exchange
A private telephone network, used by a business or enterprise. PBX systems allow a group of users to share outside lines, and use features such as call forwarding. 



POTS
Plain Old Telephone Service.
The term refers to the standard telephone service that most homes use. The POTS network is also called the PSTN.



Protocol
An established rule for communication between multiple devices or computer systems. For example, the initiation and termination of an IP telephone signal is managed over the SIP protocol. In this way, it can be called a process handling protocol. Other well known protocols include TCP/IP and HTTP.  



PSTN
Public Switched Telephone Network
Also referred to as the Plain Old Telephone Service (POTS). It is the aggregation of circuit-switching telephone networks. The public, analog telephone system.  



RTP
Real Time Protocol:
Internet protocol standard that specifies a way for programs to manage the real-time transmission of multimedia data. Originally specified in IETF Request for Comments (RFC) 1889. RTP is commonly used in Internet telephony applications. RTP does not in itself guarantee real-time delivery of multimedia data.  



SIP
Session Initiation Protocol
IETF standard protocol for initiating an interactive user session that involves multimedia elements. It is an ASCII-based protocol that provides telephony services similar to H.323, but is less complex and uses fewer resources. It creates, modifies, and terminates sessions with one or more participants. Such sessions include Internet telephony and multimedia conferences. SIP is a request-response protocol, dealing with requests from clients and responses from servers.  



Unconditional call Forwarding
All incoming calls are forwarded to pre-registered number.  VoIPVoice over IP. The capability to carry normal telephony-style voice over an IP-based Internet or data links with POTS-like functionality, reliability, and voice quality.



VoIP
enables a router to carry voice traffic (for example, telephone calls and faxes) over an IP network. In VoIP, the DSP segments the voice signal into frames, which then are coupled in groups of two and stored in voice packets. These voice packets are transported using IP in compliance with ITU-T specification - H.323, SIP, MGCP.



VPN
Virtual Private Network.
Enables IP packets to travel securely over a public TCP/IP network by encrypting all traffic from one network to another. A VPN uses "tunneling" to encrypt all information at the IP level.