Refer to the exhibits.

When the IP phone 2001 places a call to 9011 49403021 56001, the call is sent to the Cisco
Unified Border Element as 40302156001 which is what the ITSP expects to receive. The ITSP
support personnel claim that they never saw the call. Issuing the debug CCSIP message
command on the Cisco Unified Border Element results in the message “SIP/2 0 404 Not Found”.
Refer to the Cisco Unified Border Element configuration, debug voice dial and ccsip messages
exhibits. Which situation can cause this issued?

A.
The Cisco Unified Bolder Element is configured as an MGCP gateway also so that the call is
attempted via the PSTN

B.
The command allow-connections sip to h323 is missing

C.
SIP error 404 means that a codec mismatch occurred Cisco Unified Communications Manager
is sending the call as an early offer with G.711 codec.

D.
The Cisco Unified Communications Manager is rnisconfigured. The SIP invite should be sent to
the ITSP at 10.1.2.1.2. The debug ccsip message shows the SIP invite being sent to 10.12.1.2.

Explanation:
Explanation- As we can see in logs, the call is between two different signaling
devices i.e. SIP and H.323 hence The command allow-connections sip to h323 is mandatory.
Link- http://www.cisco.com/en/US/docs/ios/voice/cube/configuration/guide/vb-gw-h323sip.html