fecfeefa_Internal_Error_Codes___DocWiki__Descriptor
[Code] 31 [Explanation] Failure to set up a call occurred on a deleted interface. This condition may happen if a call comes on an interface while the interface is being hot-swapped. [Category] 182 [Descriptor] 
Interface deleted
Cisco IOS Voice Troubleshooting and Monitoring -- Cisco VoIP Internal Error Codes - DocWiki