Hi Iñaki, Iñaki Baz Castillo wrote: > El Sábado, 24 de Octubre de 2009, Bogdan-Andrei Iancu escribió: > >> So you actually can have a highly scalable signalling B2BUA - the >> opensips module could be used to locally (on opensips) interpret the >> REFER and do the call transfer, totally transparent to the other party. >> > > Hi Bogdan, even if that sounds look let me be the "bad boy" ;) > OK, let;s play good-cops and bad-cops to get the best of it ;) > - What about the implicit NOTIFY during the REFER transaction? > B2BU will take care of the entire transfer signalling (sending the NOTIFY with the state of the transfer) > - What about if parallel forking occurs during REFER transaction? > from b2bua, there are 2 distinct calls : (1) one already established, between B2B and transferred party and (2) a new one from the b2b to the transferee party - The b2b will finally wait for a 200 OK, so there is no risk if the new call is doing any kind of forking (like no UA is affected by the forking done by a proxy) > A more complex case: > > - A is speaking with P (PSTN provider). > - A sends a REFER (Refer-To: B). > - OpenSIPS handles the REFERa and generates an INVITE to B. > - Which codecs does it use? > none :) - the re-INVITEs in b2bua are done with INVITEs without SDP, so that the SDPs are directly exchanged between end parties. > - B sends 180 during 10 seconds. > - Before B answers or declines the call, P sends a re-INVITE to A. > - What does then happen? note that a re-INVITE shouldn't take place > in middle of a REFER transaction (but P kwnos *nothing* about > the REFER transaction since OpenSIPS b2bua handled it!). > This is good question - and mainly because of how should be done and not because you cannot do it. Depends how you do the transfer scenario in B2BUA: (1) once you received the REFER from A, the b2bua can hung up the P leg (unattended transfer) (2) if P leg is still kept and B2B receives a re-INVITE from there, it should deny it...what is the proper SIP response ? hmmm:D > Like this I can imagine hundreds of real cases in which, personally, I expect > b2bua module wouldn't behave correctly. > I agree that a b2bua is more complex than a proxy, but I guess the idea is to identify all these buggy cases and fix them.
Thanks and Regards, Bogdan -- Bogdan-Andrei Iancu www.voice-system.ro _______________________________________________ Users mailing list Users@lists.opensips.org http://lists.opensips.org/cgi-bin/mailman/listinfo/users