What are the ways to troubleshoot if inbound calls fail on the PRI / BRI interface? what possible debugs can help? ( sh isdn status)
Every engineer's dream debug is
debug isdn q931.
Two keys things you need to observe are
1. Cause code
2. Direction of disconnection.
With the cause codes you will be able to know the reason why the call was disconnected.
The directin of the disconnection will tell you which party initiated disconnect, this will help you know if the problem is coming from your gateway or the Telco.