I have a Cisco CP-7821-K9 IP phone that I recently converted to Third-Party Call Control (3PCC) to use with an alternate service provider. While most functionality is working properly, I'm experiencing a specific issue with outbound calls:
Cannot make outbound calls
The dial pad works and numbers appear on the screen
After dialing, pressing send/dial produces no response
No call attempt is initiated
No error message displayed
No audio feedback (no dial tone, busy signal, etc.)
Has anyone encountered similar issues when converting a Cisco 7821 to 3PCC? Could this be related to dial plan configuration or SIP trunk settings? Any guidance on troubleshooting outbound call routing would be greatly appreciated.