c8fa26c0_Internal_Error_Codes___DocWiki__Descriptor
[Code] 23 [Explanation] The system failed to select an available interface among the trunk group specified for use by a matching dial peer. [Category] 182 [Descriptor] 
Trunk-group select fail
Cisco IOS Voice Troubleshooting and Monitoring -- Cisco VoIP Internal Error Codes - DocWiki
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