On Wed, Aug 12, 2009 at 8:28 AM, Matt White<[email protected]> wrote: >>>It appears Bandtel does not apparently handle re-INVITE with no SDP >>>correctly, >>> >>>Please report the problem to them. >>> >>>Ranga > > Official answer from Bandtel > > "we do not support reinvite without an SDP, this is a grey area in the RFC it > is not a rule that is a MUST. on transfer or on hold the proper format is and > RTP destination of 0.0.0.0 and the sendonly attribute. The call is dieing > because verizon and other DID carriers do not support that either so it is > one of those things that SipX/Nortel decided they wanted to do because it > says they may do it."
Regardless of which ITSPs support it, it is a requirement of the offer-answer model that re-invite with no SDP attribute return an offer. This offer can be the same as the original offer but it is a protocol error to return OK with no SDP body. Note (thanks to Dale for digging this out for me) : RFC 3261, section 13.2.1, especially: Concretely, the above rules specify two exchanges for UAs compliant to this specification alone - the offer is in the INVITE, and the answer in the 2xx (and possibly in a 1xx as well, with the same value), or the offer is in the 2xx, and the answer is in the ACK. All user agents that support INVITE MUST support these two exchanges. I have to say it is not a valid argument to state that it is OK to make this error because Verizon "and other DID providers" do. I have some code to try to compensate for this particular error. It has not been my priority to make this hack work. If you wish you can supply your SIP credentials and I can try to get it to work on 4.1 as time permits. Regards, Ranga. > > So it looks like Bandtel will plain not work with SipXbridge...we should > probably update the wiki to remove them or make note that they do not work. > > -M It is not a MAY rule I have a hack that tries to compensate for that lack of SDP. However, apparently that hack is not smoothly working. If you want me to experiment and try to get that to work (in 4.1 - not 4.0). > > -- M. Ranganathan _______________________________________________ sipx-users mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-users Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-users sipXecs IP PBX -- http://www.sipfoundry.org/
