Incoming calls from a Public Switched Telephone Network (PSTN) through a H.323 gateway could fail with these symptoms:
- No ringback, silence or dead air. For more information, refer to these Cisco Technical Assistance Center (TAC) Case Collection cases:
- Busy tone. For more information, refer to A busy tone is received when the user calls across a gateway over a dial peer with a default codec: A busy tone is received when the user calls across a gateway over a dial peer with a default codec.
- Call never completes.
Reorder tone. Refer to Incoming calls to IP phones through an H.323 gateway fail with a re-order tone Incoming calls to IP phones coming through an H.323 gateway fail with a reorder tone.
For incoming call connection issues through a Media Gateway Control Protocol (MGCP) gateway, refer Incoming calls from a PSTN to a IP Phone by way of MGCP or a Skinny gateway get disconnectedIncoming calls from a PSTN to a IP Phone by way of MGCP or a Skinny gateway get disconnected.
To resolve incoming call connection issues, perform these steps:
- Issue the debug voip ccapi inout command on the Cisco IOS Software gateway and ensure the terminal monitor is also on.
- Place a test call from the PSTN and save the debugs. If no debug messages are displayed, the call setup messages may not have arrived at the gateway. Contact your service provider.
- Look at the debugs from the H.323 gateway and get the traces from Cisco CallManager. Follow the procedure in Setting up Cisco CallManager Traces for the Cisco Technical Support.
- If the incoming circuit is a T1 or E1 PRI, ensure that the circuit is up by following the procedures in T1 PRI Troubleshooting. If the circuit is up, use the Q.931 translator that ships with Cisco CallManager to analyze the failure code. The tool can be found at C:\Program Files\Cisco\Bin. Compare the output with what is available in the debugs described in Troubleshooting and Debugging VoIP Call Basics.
- If the incoming circuit is a T1 Channel Associated Signaling (CAS) circuit, refer to the debug voip ccapi inout section of Troubleshooting and Debugging VoIP Call Basics.
- If the incoming circuit is an analog recEive and transMit (E&M) or analog Foreign Exchange Office (FXO) and Foreign Exchange Station (FXS) port, verify that those circuits are operational. For more information, refer to these Cisco TAC Case Collection cases: