When I make a call from PBX to Exchange 2010, I always get forbidden SIP response from UM, and I check the Eventlog in UM, I found the following error:
"Watson report about to be sent for process id: 4616, with parameters: E12, c-RTL-AMD64, 14.00.0639.011, UMworkerprocess, M.E.UM.UMCommon, M.E.U.U.ValidateArgument.NotNullOrEmpty, System.ArgumentException, 893e, 14.00.0639.011. ErrorReportingEnabled: False"
