Ramachandran Iyer wrote:
Paul,
Appreciate the details u have put across... yes B2BUA is loosely
defined... with different interpretations..
I agree with .. >>It does'tn have to do MEDIA but >> I am not very
clear as to why u say it does'nt have to initiate a new call.. or answer
calls..
A UA doesn't have to initiate calls, or answer calls. It might do only
one or the other. Or it might do neither. (It might only do subscribe
and handle incoming notify. Or it might only do PUBLISH. Or it might
only do OPTIONS.)
Of course a UA has to do *something* to be useful, but there are lots of
possibilities. This same extends to B2BUA:
- it might only initiate calls and not answer them. (e.g. click to dial)
- it might only answer them and not initiate
- it might only relay MESSAGEs
- it might only relay SUBSCRIBE and NOTIFY
- it might handle a call on one side, do text to speech,
and send/receive MESSAGE on the other side.
B'cos as per what it stands for (Back-2-Back-UA)... which means for UAC
is will act as a UAS.. so ansering that call,,and for the actual UAS...
it will behave as a UAC,,and so originating the new call,,
It doesn't have to work this way, though it may. See above.
I would think of B2BUA as some1 who bridges both ends (UA's) simialr to
a proxy, but both legs being different calls.. so that B2BUA has control
over the call.. for billing purpose etc,,
This is one sort of B2BUA.
if it intends to broker other
services ...and present collated billing to say the Softswitch..etc.. or
whatever application one intends to build it for.
Can you also talk more about. Is this comment for the same context...
- conference focus
A conference focus can be thought of as a B2B2B2B...2BUA. It is
coordinating its actions among a bunch of UAs. But it in general isn't
relaying sip messages directly among those UAs.
- message exploder
Something like a one-way conference focus for MESSAGE. Receives one
MESSAGE in as a UAS, and acts as a UAC sending out copies of the message
to several targets. It has a coordinated UAC and UAS, and so is a B2BUA.
Paul
Rama
*/Paul Kyzivat <[EMAIL PROTECTED]>/* wrote:
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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