Hi Inaki You can refer to the 3GPP standard TS 24.229 for various definitiona of B2BUA. For e.g B2BUA acting as Initiating B2BUA, as a Routing B2BUA or as a terminating B2BUA or as an ALG, 3PCC, etc.
Regards Ranjit -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Iñaki Baz Castillo Sent: Saturday, August 16, 2008 6:51 PM To: [email protected] Subject: [Sip-implementors] Any RFC documenting a B2BUA? Hi, the only reference to B2BUA concept I find in RFC 3261 is: Back-to-Back User Agent: A back-to-back user agent (B2BUA) is a logical entity that receives a request and processes it as a user agent server (UAS). In order to determine how the request should be answered, it acts as a user agent client (UAC) and generates requests. Unlike a proxy server, it maintains dialog state and must participate in all requests sent on the dialogs it has established. Since it is a concatenation of a UAC and UAS, no explicit definitions are needed for its behavior. Well, the fact is that the real world uses B2BUA's and session border controllers and not just proxies to communicate with others. For example, Company_A and Company_B use SIP internally and the same SIP provider for PSTN calls. If an user in Company_A calls Company_B PSTN number the call will do: [EMAIL PROTECTED] B2BUA_A SIP_PROVIDER B2BUA_B [EMAIL PROTECTED] INVITE B_PSTN ----------> -----------> -----------> ---------> So I really don't understand why all the SIP related RFC's imagine a happy world plenty of proxies that is (and will be) false forever. However, I don't find any documentation or references about the behaviour of a B2BUA. For example: - Is legal for a B2BUA to change completely the "From" in the second leg?: User1 B2BUA User2 INVITE ---> From: user_1 INVITE ---> From: bob - Should a B2BUA allow unknown headers from leg 1 to leg 2? or should it create a completely new request from scratch? - Can be problems if B2BUA copies in leg 2 the same "Call-Id" and "From_tag"? Thanks. -- Iñaki Baz Castillo <[EMAIL PROTECTED]> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
