The method that is called when media description answer is required for an outgoing 200 OK response or an outgoing ACK when the initial INVITE request had no offer.

The method that is called when media description offer is required for an outgoing INVITE request or an outgoing 200 OK response to an INVITE request with null offer.

The method that is called when a media offer is received by the inviter in response to the original reinvite with a null offer.

The method that is called when media renegotiation (ReInvite) is received. This happens when the remote sends another INVITE request inside an existing INVITE dialog to renegotiate media description.

The method that is called when media description response is received in a 200 OK response or ACK message for an INVITE request.