Page 124 - Voice Over IP Basics Appendix B: Concepts
Gatekeeper
Terminals are the LAN client endpoints that provide real time two way
communications. When an endpoint is switched on, it performs a multicast
discovery for a gatekeeper and registers with it. Thus the gatekeeper knows how
many users are connected and where they are located. The collection of a
gatekeeper and its registered endpoints is called as a zone. A gatekeeper is
required to perform the following functions:
• Address translation
Translation of an alias address to a Transport Address using a table updated
via Registration messages.
• Admissions control
Authorization of LAN access, using Admissions Requests or Confirm and
Reject (ARQ/ARC/ARJ) messages. Access is based on call authorization,
bandwidth or some other criteria.
• Bandwidth management
Support for Bandwidth Request, Confirm and Reject messages, or a null
function that accepts all requests for bandwidth changes.
• Zone management
The Gatekeeper provides the above functions for terminals, MCUs, and
Gateways, which are registered in its Zone of control.
SoftPhone
The term SoftPhone refers to a IP extension, a dedicated LAN attached H323
compliant device, or a Software programme running on a multi-media PC. An
example of a H323 software phone is MS- Netmeeting (3.x).
Page 124 - Appendix B: Concepts INDeX IPNC Cassette Administration Manual
Voice Over IP Basics 38DHB0002UKDD – Issue 7 (22/11/02)
