Cyprus VoIP wrote: > Yes. I saw the message and the required addition in the sip.conf. The > problem is that if I set it to 72, other terminating gateways that > support 400 or more would also be limited to 72.
This is incorrect. First, you would not set it to 72, since the endpoint is already telling you 72; you would set it to something higher. Second, as the documentation states (and my email stated), this a minimum threshold. It does not override the value provided by the endpoint unless the provided value is *lower*. All of this you would know if you had already tried it, which probably would have taken less time than writing the two emails about it have taken :-) > What doesn't make sense is Asterisk's "commission". Why doesn't it > simply pass/use whatever it gets without cutting the values? It looks > like it's a bug. It is not a bug. Asterisk has to deconstruct incoming UDPTL frames when they are received, pass them through a bridge, and then construct new ones on the outbound side. To do this, it has to have knowledge of what the maximum IFP size each endpoint can receive is, and compute a reasonable T38FaxMaxDatagram value to tell the *other* endpoint (taking into account the error correction mode(s) in use) so that when it receives a UDPTL frame from endpoint A it can be reasonably assured it will be able to forward it to endpoint B without violating endpoint B's max datagram size... but when endpoint B has told Asterisk a ludicrous max datagram size, it must be overridden somewhere to allow FAXes any reasonable chance of working. > Alternatively, I could (had I known how ;-)) set this ATA not to relay > the RTP via Asterisk, in which case maybe Asterisk would leave the > values unchanged. When I use another port on this ATA from the same > location to the same destination without passing through the Asterisk, > the faxes go through. How should I define this peer in sip.conf so that > Asterisk wouldn't relay the RTP for it? T.38 FAX can use RTP, but almost never does; in all of the cases you are dealing with, it is using UDPTL for media transport, not RTP. Asterisk does not yet support direct UDPTL media between endpoints, so that's not an option for you. That's not necessary, though, because clearly when you tell those two endpoints to talk directly to each other, the one that receives 'T38FaxMaxDatagram: 72' is *ignoring* that restriction and sending larger packets... it has to, or the FAX would fail. Asterisk doesn't do that automatically, for safety's sake, it tells the administrator when this problem is occurring and how to overcome it. -- Kevin P. Fleming Digium, Inc. | Director of Software Technologies 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA skype: kpfleming | jabber: kpflem...@digium.com Check us out at www.digium.com & www.asterisk.org _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
