What is the design intent of Asterisk when it receives a re-invite with no SDP? Bug 14385 seems to focus on this point, but I can’t tell clearly determine the design intent from the bug chatter.
Broadsoft, cisco, and others use such a re-invite to solicit media capabilities, such as when taking a call off hold. This signaling functions in this manner when sent to large SIP carriers as well, so there seems to be fairly wide support of this paradigm.
A requirement to handle this signaling was mentioned in tools.ietf.org/html/draft-ietf-sip-rfc2543bis-04, but did not make it into 05 or subsequent docs.
Is it the intent of the asterisk developers to view a re-invite with null SDP as a capability solicitation and to respond to such a packet with an SDP offer containing all media capabilities?