Hi Todd, INVITEs without SDP are perfectly legit, they are usually used by the inviter to get the full list of supported codecs of the phone.
Because on a regular INVITE with SDP some phones select/provide only one of the codec in the response SDP and the inviter is not aware of all the other supported codecs. In the case of INVITEs without SDP, the phone usually gives all its supported codecs in the response SDP, and the inviter selects/provides its codec(s) in the SDP of the ACK sent after receiving the response. It's some kind of inverted offer/answer if you prefer. Regards. _______________________________________________ sipx-dev mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-dev/
