You recently configured a system for B2B SIP URI calls, and users confirmed that they could make calls. You are receiving multiple reports that inbound calls are failing and that users are not receiving calls to their URI. You confirm that all zones between expressways are active, and the trunk between Cisco Unified Communications Manager and Cisco VCS Expressway is active. You also see that the inbound call is sent from Cisco VCS Expressway C to Cisco Unified Communications Manager. Why are the calls failing?

A.	The Cisco Unified Communications Manager FQDN was not set.
B.	The cluster FQDN was notset in Enterprise Parameters.
C.	The certificate is not valid.
D.	The cluster FQDN was not set in Service Parameters.
E.	The FQDN was not registered in DNS.