Technical Report TR/87
Using CSTA for SIP Phone User Agents
The Session Initiation Protocol (SIP) is a control (signalling)
protocol for creating, modifying, and terminating sessions with
one or more participants. These sessions include Internet telephone
calls, multimedia distribution, and multimedia conferences.
by a SIP user agent on a SIP phone;
can also be implemented by a SIP B2BUA to augment 3PCC functionality;
a proxy server that is front-ending a PBX.
CSTA standardizes a very powerful and flexible set of application
services to observe and control voice and non-voice media calls
as well as control and observe non-call related features.
This Ecma Technical Report describes how CSTA can be used to provide
a subset of CSTA call control functionality, called 1st party
call control, for SIP user agents. The term uaCSTA (for user agent
CSTA) refers to transporting ECMA-323
(CSTA XML) messages over a SIP session.
uaCSTA leverages SIP mechanisms to provide a highly featured,
robust, and extensible set of features to support applications
in the Enterprise environment.
uaCSTA can be implemented by several different types of SIP user
The following file can be freely downloaded:
|| Acrobat (r) PDF file
This Ecma publication is also approved as ISO/IEC TR 22767