In CUCM 7.1.3 we registered the Nortel 1120 SIP Phone. Phone is registred & from there we able to calls the numbers internally with in the cluster.
If i dialed some external numbers i'm getting fast busy reorder tone.
In CUCM logs we are getting "SIP 503 Service unavailable & unable to find the device handler".
"unable to find the device handler "----- what is it mean exactly ? with 503 messages we understood that CUCm itself unable to process the request.
Thanks in advance