SDP message in INVITE


I just want to know that some devices are sending SDP in first INVITE Message and some are not. What is the Asterisk behavior in this regard?

Lets say CIsco CUCM doesn’t send SDP message in INVITE Message. Will Asterisk accept call from Cisco CUCM without SDP information?

Asterisk handles late offer, although at least some versions have some issues with handling it on re-invites. Cisco is the only system I ever remember doing late offers and whether or not it does them depends on whether it intends to pass the RTP directly between the endpoints, or not (although I can’t remember which way is which).

The problem that Asterisk has, at least in 1.6.1, is that it offers the current negotiated state if there is an incoming late offer re-invite, when it should offer the starting state (all capabilities and call not held).