Troubleshooting outbound calling issues with Cisco 7960 series VoIP phones can involve several steps. Since you've already checked DNS, IP addresses, and basic configurations, here are some additional areas to explore:
1. Check Dial Plan Configuration
Dial Patterns: Verify that the dial patterns configured on the phone match the expected dialing patterns for outside numbers. For example, if users need to dial "9" for an outside line, ensure this is configured correctly.
Number Manipulation: Ensure that the phone is configured to send the appropriate digits to the call manager or PBX. Sometimes, certain digits might need to be stripped or added for calls to go through.
2. Review Call Routing
Route Patterns: In Cisco CallManager (CUCM) or the call control system you are using, check the route patterns or route lists to ensure that calls to outside numbers are allowed and routed correctly.
Route Plan Report: Generate a Route Plan Report in CUCM to see how calls are being processed. Look for any misconfigurations or overlaps in dial patterns.
3. Verify Trunk Configurations
Trunk Groups: If you are using SIP trunks or other types of trunks, ensure that the trunk groups are configured correctly. Check if the trunk is active and able to make outbound calls.
Dial Peer Configuration: If using a Cisco router for VoIP gateway functionality, review the dial peer configurations to ensure they are pointing to the correct destination.
4. Call Privileges and Class of Service
User Permissions: Check if the user accounts associated with the phones have the necessary permissions to make outbound calls. Verify the calling search spaces and partitions assigned to the phone.
Class of Service: Ensure that the phones are assigned to the correct class of service or calling profile that allows outbound calls.
5. SIP Registration and Authentication
SIP Credentials: If using SIP for signaling, ensure that the SIP credentials (username, password) configured on the phone match those expected by the SIP provider.
Registration Status: Check the SIP registration status of the phone. If it's not registered or has registration issues, outbound calls may fail.
6. Network Connectivity
Firewall Rules: Verify that there are no firewall rules blocking outgoing SIP or VoIP traffic.
Quality of Service (QoS): Ensure that QoS settings are configured correctly to prioritize VoIP traffic, especially if there are issues with call quality or call setup.
7. Debugging and Logging
Call Logs: Check the call logs or call detail records (CDRs) to see if the calls are being attempted and where they are failing.
Debugging Tools: Use debugging tools on the call control system (CUCM, PBX) or router to trace the call flow and identify any errors.
8. Firmware Updates
Firmware Compatibility: Ensure that the firmware version on the Cisco 7960 phones is compatible with the call control system or SIP provider.
Firmware Upgrades: Consider upgrading the firmware on the phones to the latest compatible version. Sometimes, firmware updates can resolve compatibility issues.
