Amarendra,
The term B2BUA is very general, and implies very little. It has only
one responsibility: to act as a UA, in each direction that it faces.
- It isn't required to initiate calls at all.
- It isn't required to answer calls directed at it.
- It isn't required to do anything with media.
Almost everyone that asks questions about B2BUAs has something more
specific in mind - something that is a specialization of a B2BUA with
some specific intent in mind.
There are a few kinds of things that are being standardized by the IETF
that happen to be UAs:
- conference focus
- message exploder
Another thing that is under discussion, and that is loosely understood,
is a Session Border Controller. (I say loosely understood because you
will probably get a different set of detailed requirements from each
person you ask.) In most incarnations an SBC is a B2BUA.
Some "SIP PBXs" and SIP SoftSwitches are implemented as B2BUAs, though
there is no standards for this.
The 3GPP IMS specifications define various CSCFs that sometimes may
behave as B2BUAs.
Each of these things has its own behavior. If it is one of these things
that you are interested in, then there may be an answer to your
question. But you are asking your questions about B2BUAs in general
there is no answer.
Paul
Amarendra Kumar wrote:
Hi,
Is it the responsibility of the B2BUA establish call even if both the
end pionts don't
have compatible media codecs.
Lets say : A is trying to reach B, But both of them, don't have
compatible media
codecs.
While connecting A & B, can B2B terminate one callleg (ie. A --- B2B) at B2B
and start one more (ie. B2B-------B), also B2B will do the codec conversion for
imcompatible codecs. In this senario there will be be 2 RTP sessions
established for the single call. If so then which is the best place
for the codec
converter
1. Along with B2B
2. Independent entity (application server) which will handle all
media related stuff
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