Missed Calls Are Not Connecting to Exchange Unified Messaging
Microsoft Office Communications Server 2007 and Microsoft Office Communications Server 2007 R2 will reach end of support on January 9, 2018. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.
If missed calls are not connecting to Exchange Unified Messaging, you can troubleshoot the issue as follows:
Verify that Exchange users are enabled for Unified Messaging and are assigned to a SIP Uniform Resource Identifier (URI) dial plan that is configured for use with Office Communications Server. For details, see How to Enable a User for Unified Messaging at Microsoft TechNet at https://go.microsoft.com/fwlink/?LinkId=143015.
Verify that the Exchange administrator has installed a certificate from a certification authority (CA) that is trusted by both the Exchange Server 2007 servers and the Office Communications Server 2007 R2 servers.
Verify that the Exchange administrator has run the ExchUCutil.ps1 utility on Exchange to grant Office Communications Server permission to read the Exchange directory attributes in every forest where Exchange Unified Messaging is installed.