which debug (or) show command to trace the voice call

[IpKid]

Hi Everyone,

I would like know how to verify the call tracing between Ericsson PBX and the Cisco voice gateway and gatekeeper.
But I have no idea to use the correct command to trace the calling party and called party digit.
Actually I am looking for the solution for one of the faults at the actual site.
My existing setup is as per below:

PBX-A? E&M trunk ? 3640 router (voice GW) ? 7200 router (GK) ? switch ? PBX-B

When I made a call from PBX-A (with E&M trunk) to PBX-B (IP PBX), the called party got ring and the calling party also got ring back tone. Both parties could be able to speak each other.
But when I made a call from PBX-B (IP PBX) to PBX-A (with E&M trunk), the called party didn’t get any ring. According to the tracing from PBX-B its look like all the digits are thrown to the gateway and the PBX-A.
So I would like to trace the call whether the digits are received or not from the gateway and the gatekeeper.
Please guide me to use the proper show (or) debug command.
May I know the link (or) manual to troubleshoot this issue?
Thank you.

Best Regards,
IpKid