Iñaki Baz Castillo wrote: > 2009/2/23 Vito Korleone <[email protected]>: >> Hi everybody! I 'm a new member in this group of SIP people :-). >> >> So, here's my question, >> >> Why "we" need a B2BUA?? Can't we just have the same functionality if >> we replace him with a proxy and insert the Record Route field to trace all >> messages between the subscribers?? > > The following example is unfeasible with a proxy (it requires a B2BUA): > > - alice calls bob (through the B2BUA). > - bob answers and they talk for a while. > - After 20 seconds bob hangups. > - The B2BUA initiates a new leg to carol. > - alice talks with carol. > > Impossible with a proxy.
This is pretty specialized case. The main problem is that the pure RFC3261 SIP proxy, even with strict record routing, cannot forcefully end call that has been answered by generating BYE (i.e. implement duration limit). B2BUA can do it. Emphasis on "pure RFC3261 proxy" is because nowadays many of the proxies out there have B2BUA-like modules that can actually keep some call state for the duration of the dialog. Regards, -- Maksym Sobolyev Sippy Software, Inc. Internet Telephony (VoIP) Experts T/F: +1-646-651-1110 Web: http://www.sippysoft.com MSN: [email protected] Skype: SippySoft _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
