this fixed our problem.
Your proxy domain name is in upper case, you could be running in to this bug.
CSCsl63971:case-sensitivity on proxy domain causes CUPC problems
please change the proxy domain to lower case and restart the proxy services, directions are as follows
web page -> system -> service parameters -> Cisco UP SIP Proxy -> Proxy Domain.
Then go to Serviceability web page -> Tools -> Control Center - Feature Services, restart the Cisco UP SIP Proxy service