Core Issue
The CallManager Express system fails to forward calls to Public Switched Telephone Network (PSTN) numbers. The debug voice ccapi ino command output shows that everything is good until the call is disconnected. The disconnect reason is listed as Transfer Number Is Null.
Resolution
Use the show ephone cfa command in order to list registered ephones that have call-forwarding-all (cfa) activated on one or more ephone-dns.
Router#show ephone cfa
Issue the telephony-service dial-peer command:
Router#show telephony-service dial-peer
Use the debug ephone commands in order to observe messages and states associated with an ephone. Refer to Cisco Unified CME Command Reference for more information.
Also make sure telco does not drop the call due to an invalid IE. It can be verified from the debugs, and if this is the case, then add:
On relevant POTS dial-peers:
progress_ind alert enable 8
progress_ind progress enable 8
progress_ind connect enable 8
On relevant VoIP dial-peers:
progress_ind setup enable 3
In order to enable the terminating gateway to send an alert message instead of a progress message after it receives a call setup message, use the voice call send-alert command in global configuration mode. In order to reset to the default, use the no form of this command. Refer to the Call Transfer and Call Forwarding section of Cisco Unified Communications Manager Express System Administrator Guide for more information about call forwarding configuration and issues.
Issue the show telephony-service all or the show command in order to display call forwarding configurations for ephone-dn dial peers.
