El Miércoles, 29 de Abril de 2009, Dan Pascu escribió: > You realize that a B2BUA completely separates the 2 call legs, which > includes audio.
I mean "SIP transparent B2BUA" which doesn't handle media and doesn't touch the SDP at all. > If you only attempt to split the signaling path, but leave > the media path to flow directly, you may have trouble with NAT. For that I have a proxy calling a media-proxy when needed, but if both users are behind the same NATm using the media-proxy is not required (and this is the example I described). > So if you > replace a media relay with a B2BUA which does media transcoding, I do not > believe you are any better. I've never told about B2BUA with media transcoding. > > Imagine a company using a hosted virtual PBX solution (the > > proxy/SA/B2BUA has public IP while the phones are behind NAT). > > Imagine the boss wishing to have an accurated log (cdr) of how long > > his employers are speaking between them. These calls take place, > > probably, into the same LAN so a media-proxy is not required to allow > > bidirectional audio. > > It may not be required, but it can be used to get some additional > benefits, even more in this particular example, considering that LAN > traffic is cheap. LAN traffic is cheap? perhaps I should describe again the scenario I described: A company using a *hosted* virtual proxy/PBX service. The provider (the proxy/B2BUA is in some datacenter while the phones are in the company office behind a NAT router). There is no media-proxy in the LAN. If you force a media-proxy it should take place out of the office (so comsuming ADSL/SHDSL/... bandwith). > > Also, forcing a media-proxy could consume high bandwitch and create > > audio delay. > > This is actually incorrect. A media relay should be positioned next to the > PSTN gateway, so that the network will not see more traffic than it would > have seen if the media streams would have reached the gateway directly. In my example, I clearly spoke about a conversation between two phones in the LAN. With your suggestion (using a media-proxy to ensure the accounting reliability) the audio would go and back to the provider datacenter (in which the media-proxy resides). Regards. -- Iñaki Baz Castillo <i...@aliax.net> _______________________________________________ Users mailing list Users@lists.opensips.org http://lists.opensips.org/cgi-bin/mailman/listinfo/users