I wrote this basically for my own remembering:
1. show call leg active / sh call leg act sum
Helps find active calls running on the voice gateway live.
2. sh call leg act | in Port
Helps filter which ports are being used in case I need to follow it with “shut/no shut” to reset hang ports.
3. csim start <number_to_dial>
Initiate a call from the voice gateway to the number.
Very helpful in troubleshooting voice routes.
4. debug voice ccapi inout / debug cch323 all / debug ip tcp transaction
Along with “csim” and “terminal monitor” it can provide great tool.
5. Check TCP ports on CUCM
As simple as “telnet <ip_address> 1720 / 1719 / 2000 / 2001” can help pointing a communications issue.