Cisco MGCP IP Phone Administrator's Manual page 16

What Is the Cisco MGCP IP Phone?
MGCP provides the capabilities to allow a Control Server to:
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Note Conferences can consist of two or more users and can be established using multicast or multiple unicast
sessions. The term conference means an established session (or call) between two or more endpoints. In
this document, the terms conference and call are used interchangeably.
MGCP is a client-server protocol. The CA handles all aspects of setting up calls to and from endpoints.
CAs or control servers provide the feature capabilities that a particular endpoint will be able to use.
Endpoints connected to different CAs will likely have a different set of features they can use. Since all
of the call control features are in the control server, each control server vendor decides which features
are most important, and therefore different control server vendors differ in "essential features."
What Is the Cisco MGCP IP Phone?
The Cisco MGCP IP Phone provides voice communication over an IP network. It functions much like a
traditional phone, allowing you to place and receive telephone calls.
The Cisco MGCP IP phone works with a third-party CA that uses MGCP for call control and Basic
Telephony eXtensible Markup Language (BTXML) for control of the phone's displays and feature keys.
This document describes the phone features that are controlled by the phone. Refer to your CA
documentation for descriptions of all other phone features, displays, and applications.
Cisco MGCP IP phones are full-featured telephones that can be plugged directly into an IP network and
used very much like a standard PBX telephone. The Cisco MGCP IP phone model terminals can attach
to the existing in place data network infrastructure, via 10BaseT/100BaseT interfaces on an Ethernet
switch. When used with a voice-capable Ethernet switch (one that understands Type of Service [ToS]
bits and can prioritize VoIP traffic), the phones eliminate the need for a traditional proprietary telephone
set and key system/PBX.
Figure 1-1
Cisco MGCP IP Phone Administrator Guide, Release 5.0 and Release 5.1
1-2
Determine the location of the target endpoint.
Determine the media capabilities of the target endpoint. Using Session Description Protocol (SDP),
MGCP determines the lowest level of common service between the endpoints. Conferences are
established using only the media capabilities that can be supported by all endpoints.
Determine the availability of the target endpoint.
Establish a session between the originating and target endpoint. If the call can be completed, MGCP
establishes a session between the endpoints. MGCP also supports mid-call changes, such as the
addition of another endpoint to the conference or the changing of a media characteristic or codec.
illustrates physical features of the Cisco MGCP IP phone:
Chapter 1 Product Overview