Re: [SIP] Back-to-back UAs

Keith,

I apologize.  Back-to-back UA is another name for Rosenberg's
3rd Party Call Control.  3PCC was first published here..
http://www.cs.columbia.edu/~hgs/sip/drafts/draft-rosenberg-sip-3pcc-00.txt
The draft does not use the B2BUA moniker.

Yes, 3PCC/B2BUA can break the end to end nature.  Sometimes this
is desired.  A company may wish to hide its internal
routing.  A fragile gateway may need a SIP wrapper/firewall.  etc.

The biggest problem I currently experience is 
looping.  I wish all B2BUAs would preserve 
the call-id.  Unfortunately, I can't get rid of my biggest
B2BUA, the public switched telephony network (PSTN).  :-/

--
Rick
rick_dean@3com.com

On Tue, Jan 16, 2001 at 12:57:05PM -0000, Drage, Keith (Keith) wrote:
> I keep seeing mention of back-to-back UAs and I think I understand what is
> trying to be done with them. 
> 
> I do however see an issue that there is apparently no documentation of this
> concept in any draft. Therefore it leads to the question of when does a
> proxy become a back-to-back UA, and therefore perform all error handling and
> syntactic checking as a UA rather than a proxy. Because there is no mention
> in any draft, it would probably never be identified in any conformance
> statement, and an attaching UA to this concept might therefore see behaviour
> that was not expected.
> 
> I also see problems where, because it is not documented, the impact of
> interactions with other drafts may not have been assessed. For example, is
> there an impact on the privacy draft, such that the identifiers passed using
> the concepts of the privacy draft will never pass the back-to-back UA? Do we
> have problems with any headers that have been ciphered, because we do not
> wish to release them outside proxies?
> 
> I would therefore ask, if such a concept is meant to legally exist, should
> be not at least define it somewhere. (Thats assuming I haven't missed it
> somewhere!)
> 
> Keith Drage
> Keith Drage
> Lucent Technologies
> Tel: +44 1793 776249
> Email: drage@lucent.com
> 
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