MS Released an update for OCS in November.
Issues that the update package fixes
943021 (http://support.microsoft.com/kb/943021/) Error message when you send an invitation in Communicator 2007 ‘SIP/2.0 408 Request Timeout’
943391 (http://support.microsoft.com/kb/943391/) An access violation error may occur in the Apiem.dll file when you run Microsoft Office Communications Server 2007
943880 (http://support.microsoft.com/kb/943880/) You may receive an access violation error message in the APIEM.DLL!WPP_SF_qSS call when you run a stack trace on a computer that is running Communications Server 2007″
Its mostly security related issues, and i recomend installing this on your system. The update is avalible throug Microsoft Update.
Remember to install the update on all OCS Servers
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