A B2BUA is a logical network element in SIP applications. A B2BUA operates between both ends of a phone call or communications session and divides the communication channel into two call legs and mediates all SIP signalling between both ends of the call, from call establishment to termination. This mechanism help service provider to implement metering for the calls and may also provide value added services during the call.
In the originating call leg, B2BUA acts as a user agent server (UAS) and processes the request as user agent client (UAC) to the destination end, handling the signalling between end points back to back. A B2BUA maintains the complete state for the calls it handles. Each side of the B2BUA operates as standard SIP network element as specified in RFC 3261.
Often B2BUA are implemented in Media gateways to also bridge the media streams for full control over the session.
A Signalling gateway, implemented as part of the Session Border Controller is example of B2BUA.
References:
No comments:
Post a Comment