My ISDN gateway sends SESSION PROGRESS message to 3CX without SDP and then second SESSION PROGRESS message contains the SDP information. This is because the ISDN side sends it in this manner. 3CX seems to consider first SESSION PROGRESS and ignore second SESSION PROGRESS and hence it ignores SDP information. This results in no pre-call announcements played to the caller. Is there a way that we can configure 3CX to accept second SESSION PROGRESS so that it can open media as per the SDP information.