Calls fail when they are routed from the PSTN to Office Communications Server 2007 after you update to Office Communications Server 2007 R2

After you update an Office Communications Server (OCS) 2007 Mediation server from the initial release version to the R2 release, calls may fail when they are routed from the public switched telephone network (PSTN) to OCS 2007. Also, the call-forwarding, call transfer, and ring back features may no longer work after an update to OCS 2007 R2.

In Office Communications Server 2007 R2, a Mediation server now supports the SIP Diversion Header field. During routing, the Diversion Header is changed to a Route Header. If this Diversion Header contains an unreachable destination URI, the Office Communications Server 2007 Front End Server does not send to this URI. This causes the call failure that is described in the "Symptoms" section.

To resolve this issue, apply the following update:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.