CSCeg52210

When issuing the below command and you see a $ sign next to one of your DNs you will need to install one of the IOS listed: 12.4(98.7), 12.4(2.5), 12.4(2.6), 12.4(2.7), 12.4(2.9)T, 12.4(2.11), 12.4(2.11)T, 12.3(11)T7, 12.4(3.5)T, 12.4(3.6), 12.4(3.7), 12.4(3.6)T, 12.4(3.7)T.  These releases should fix your MWI problem.
sam-cme#sh sip reg sta sec
Line                             peer                     expires(sec)          registered
============ ============= ============ ===========
2486$                         20001                        113                   no