There is no Service-Route to copy

Today I received a ticket from a branch location that stated calls to the PSTN were failing.

Looking at the snooper message log I saw a 487 Request Terminated error.



Digging for more clues, I examined the trace and found, "There is no Service-Route to copy"



Next I viewed the SBS Event log and found Event 25051 below.



Puzzled, I began asking questions and found out that the local DNS server was recently changed to a new server. Calls began working fine after I updated the primary DNS server on the NIC adapter settings for the SBS along with the static DNS entry in the AudioCodes gateway config.