Core Issue
Outgoing calls to Public Switched Telephone Network (PSTN) through an H.323 gateway could fail with these symptoms:
For outgoing call connection issues through a Media Gateway Control Protocol (MGCP) gateway, refer toOutgoing calls to a PSTN or PBX network through a MGCP gateway fail with symptoms like dead air or re-order tone
Resolution
If the reorder tone is heard after the complete number is dialed, then digit manipulation can occur at the route pattern, route list or by use of translation patterns.Refer External calls fail through the gateway router on Cisco CallManager - user hears the reorder (or fast busy) tone
To address this issue, perform these steps: