Specifications

Appendix C - Glossary Administration Manual (SIP/MGCP Version)
AT-VP504E FXS 132
G.711 ITU-T recommendation for an algorithm designed to transmit and
receive A-law PCM (Pulse Code Modulation) voice at digital bit rates of
48, 56, and 64 Kbps. It is used for digital telephone sets on digital PBX
and ISDN channels.
G.723.1 A Codec that provides the greatest compression, 5.3 Kbps or 6.3 Kbps;
typically specified for multimedia applications such as H.323
videoconferencing.
G.729/G.729A A Codec that provides near toll quality at a low delay which uses
compression to 8 Kbps (8:1 compression rate).
Gateway A device that links two different types of networks that use different
protocols (for example, between the packet network and the Public
Switched Telephone Network).
Integrated Services
Digital Network (ISDN)
An international telecommunications network, based on a set of
communications standards, for digital transmission of voice, video, and
data over WANs. ISDN interfaces also provide LAN connections and
remote access capability. ISDN has two types of service: BRI (basic
rate interface) and PRI (primary rate interface).
International
Telecommunication
Union (ITU)
Organization based in Geneva, Switzerland, that is the most important
telecom standards-setting body in the world.
Internet Protocol (IP) A standard describing software that keeps track of the Internet’s
addresses for different nodes, routes outgoing messages, and
recognises incoming messages.
Jitter
1. A distortion caused by the variation of a signal from its
references which can cause data transmission errors,
particularly at high speeds.
2. Variations in amplitude, time, frequency or phase.
Layer 2 Layer 2 refers to the Data Link Layer of the commonly-referenced
multilayered communication model, Open Systems Interconnection
(OSI). The Data Link Layer is concerned with moving data across the
physical links in the network.
The Data-Link Layer contains two sublayers that are described in the
IEEE-802 LAN standards:
Media Access Control (MAC)