‘Incompatible Security Setting’ error encountered when calling voice mail from Microsoft Office Communicator

After successfully integrating Office Communications Server 2007 with Exchange Unified Messaging, you may find that you are unable to call voice mail to check for new messages from your Office Communicator client.  Upon placing the call, you may receive an ‘Incompatible security setting’ error as shown below:

In OCS 2007 R2, both Standard Edition servers and Enterprise Pools are automatically configured to require encryption for all media exchanges.  The setting that controls this behavior can be found in the properties of the Pool object using the OCS 2007 R2 Management Console:

Previous guidance had suggested that OCS integrated Dial Plans in Unified Messaging should be configured with a VoIP security setting of ‘SIP Secured’ (require encryption for SIP traffic only).  However, this VoIP security setting on the Dial Plan is insufficient if the OCS Pool is configured to require encryption (require encryption for both SIP and RTP traffic).  If this discrepancy exists, all calls to Unified Messaging from the OCS Pool will fail resulting in the ‘Incompatible security setting’ error seen above. 

 

To resolve this issue, you have two possible options:

• Reconfigure the properties of the OCS Pool to ‘Support Encryption’ (not advised)
• Reconfigure the VoIP security setting in the properties of the UM Dial Plan to use ‘Secured’ (preferred)

 

Thanks to Geoff Clark for this solution!

 

-- Dave