VOIP Glossary of Terms Page 2 E.164 The international public telecommunication numbering plan. An E.164 number uniquely identifies a public network termination point and typically consists of three fields, CC (country code), NDC (national destination code), and SN (subscriber number), up to 15 digits in total. E1 The designation for the 2.048Mbps. ITU standard for Europe's 30-channel digital telephone service. It is the European version of T-1 (DS-1). The bandwidth is divided into two signaling channels (channels 15 and 31 starting from 0) and thirty bearer (voice channels). A&B bit signaling (robbed bit signaling) is not used here. E-1 uses one of the control channels for signaling and the other for clock synchronization. Endpoint SIP or H.323 terminal or Gateway. An endpoint can call and be called. It generates and terminates the information stream. Facility-based carrier A long-distance service provider that owns its own physical facilities. The bulk of the long-distance companies are resellers. Find-me/follow-me A feature that allows calls to find you wherever you are, ringing multiple phones (such as your cell phone, home phone, and work phone) all at once. FXO (foreign exchange office) is the interface on a VOIP device for connecting to an analog PBX extension. FXS (foreign exchange station) is the interface on a VOIP device for connecting directly to phones, faxes, and CO ports on PBXs or key telephone systems. G.711 An ITU-T PCM half-duplex codec that uses either A-law or U-law compression (64 kbps, high quality, minimum processor load). G.723.1 An ITU-T double rate CELP codec (6.4/5.3 kbps, medium quality, high processor load). G.729 An ITU-T ACELP codec (8 kbps, medium quality, high processor load). Gatekeeper A device or computer that controls one or more gateways within a 'zone'. Gatekeepers are responsible for routing all calls to/from the gateways in a non-point-to-point situation. Gatekeepers can communicate with other gatekeepers, but usually only between those of the same manufacturer. 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 PSTNs and packet-switched networks, translating the media into IP packets, so that "legacy" telephony becomes Voice-over-IP. H.323 An ITU-T standard for handling video, data and voice call information. This standard was originally proposed for the PictureTel system, which allowed video/voice calls, but has been enlarged to encompass many types of media devices. This 'protocol' is actually a umbrella for multiple protocols, each responsible for different items such as packet format and transmission, video codecs, voice codecs, call signaling, conferencing, etc. Version 1 was formally approved in 1996 and the latest, version 4, was approved in November 2000. Incumbent Local Exchange Carrier (ILEC) A U.S. telephone company that was providing local service when the Telecommunications Act of 1996 was enacted. ILECs include the regional Bell operating companies. A "local exchange" is a carrier’s local "central office", where residential and business lines terminate. Local exchanges connect to other local exchanges within a local access and transport area or to interexchange carriers such as long-distance carriers like AT&T and Sprint Interexchange Carrier (IXC or IEC) Synonymous in common usage with "long-distance carrier", an interexchange carrier (IXC) is a telephone company that provides connections between local exchanges in different geographic areas. Under the federal Telecommunications Act, an IXC carries communications traffic across LATA boundaries. BOCs, at this time, are only permitted to carry communications within LATA boundaries. Internet Telephony Any means of transmitting the human voice (real time or close to real time) over the internet. There are several components: 1) On the client side, a multimedia-equipped PC with special client software will digitize your voice. This can be done with a voice modem or other voice encoding method; 2) A direct or dial-up connection to the internet allows your voice to be transmitted in packet form to its destination; 3) Connection with the far side is achieved by IP address search, common servers or beacons to identify the called party (and to "ring" that person's phone); 4) A similar arrangement on the far end completes the call and allows both parties to speak. There are also PSTN/Internet gateways that allow regular telephone callers to make Phone-to-Internet-to-Phone connections. There are PC-to-Phone connections and Phone-to-PC connections. ISP Internet Service Provider. A business that provides subscriber-based access to the Internet. Subscribers can be individuals or businesses. According to Jack Rickard, publisher of Boardwatch Magazine, ISPs operate at the fourth or lowest level of the Internet. At the third level, regional providers aggregate traffic from lower-order ISPs to the second, backbone level. The highest level in North America is the NAP (Network Access Point), which act as peer-to-peer interconnection points for the largest backbones. There are three "official" NAPs located in San Francisco, Chicago and Pennsauken, New Jersey. ISPs use both Internet Routers, Servers and Rack-Mounted modems to provide a variety of services including Web Site hosting, FTP service, e-mail accounts, unified messaging, audio and video broadcasting and in some cases - Internet Telephony and Fax Gateway service. IETF The Internet Engineering Task Force is the organization responsible for defining standards that affect or use the IP network. Internet Protocol (IP) The method by which data is sent from one computer to another on the Internet. Integrated Services Digital Network (ISDN) A point-to-point signaling protocol designed to interface PBX equipment with central office switches. IP Centrex IP Centrex delivers such services as call hold, call transfer, last number look-up and redial, call forward, three-way calling, but does it on a packet-based network. IP PBX IP PBX is a customer premises telephone system that manages telephones in the enterprise and acts as the gateway to external networks. Unlike a conventional PBX that requires two separate networks, one each for data and voice, an IP PBX is based on converged networks that enable true one-wire to the desktop connection. An IP PBX can be used with IP phones, softphones and traditional phones connected to Ethernet adapters (ATA) or PCs.   <Prev Next>