Upon opening a case with MS, the 2nd SIP re-Invite we are receiving does not have any changes in the SIP SDP, specifically in the "c" line (MSS 2007 doesn't allow for media codec changes). There is no way to influence or adjust MSS 2007 to work around
this issue. We updated the IOS on the Cisco Voice Gateway, which then passed the 488 on to the sender, and allowed the call to continue vs. Cancel, which is what was happening before the IOS update.
Marked as answer byDanFoxleyThursday, April 14, 2011 5:46 PM