A missed call notification could not be generated. Dial plan %1 does not have any Exchange UM servers defined. Failure occurrences: ...

A missed call notification could not be generated.

Dial plan %1 does not have any Exchange UM servers defined.
Failure occurrences: %2, since %3.
Cause: The user may have been assigned to a dial plan that is incorrectly configured or the UM server(s) in the dial plan may be invalid.
Resolution:
Check the configuration for this dial plan and point it to appropriate Exchange UM servers.