Based on the information in the exhibit, what is causing the problem?

Refer to the exhibit.

You have configured enough SIP channels to carry the expected communications load, but users are reporting that sometimes they cannot call out and callers cannot get through.

Based on the information in the exhibit, what is causing the problem?
A . The system is ignoring refresh messages.
B . The caller ID is not passed by some carriers.
C . The calls are being referred incorrectly.
D . The timer should be set to 2 minutes.

Answer: B