Refer to the exhibit. 
You have received a trouble ticket stating that calls to international numbers
are failing. To place an international call, users dial the access code “9,” followed by “011,” the
country code, and the destination number. After entering the debug isdn q931 command on the
MGCP gateway, you have the user attempt the call again.
Based on the debug output, what is the most likely cause of this problem?
A.
Cisco Unified CallManager is not stripping the access code before sending the call to the
gateway.
B.
The gateway dial peer needs to prefix “011” to the called number so the PSTN knows this is an
international call.
C.
The user’s CSS does not permit international calls.
D.
The TON is incorrect.
E.
The circuit is not configured correctly or has a physical layer issue.
Explanation:
This question is to test the troubleshooting of the call failure via the debug information.
According to the debug information, the channel requested by the call is unavailable. There are
two reasons:
1. The channels used by two endpoints are different;
2. Because of the configuration error, the connection cannot be established.
Cause No. 44 – requested circuit/channel not available [Q.850] This cause is returned
when the circuit or channel indicated by the requesting entitycannot be provided by the other side
of the interface.