I have a 2811 with 12 FXO ports and 12 POTs lines. 6 of the lines are in a trunk group for outbound calling. When making outbound calls I get a 1/3 failure rate, with the caller receiving a fast busy. Is there a way to debug the calls and see which voice ports are failing and which are successful? Or are there any other suggestions?
When making the outbound call, do a "show voice port summary" on the gateway. This will allow you to see which port the call is attempting to use.
Hope this helps. If so, please rate the post.