Phone A is able to dial the directory number of Phone B and complete a call. However, when Phone B dials the directory number of Phone A, Phone B receives a fast-busy tone. What is causing this issue?
A. Phone A and Phone B are in different partitions.
B. Phone B does not have Phone A in its partition.
C. Phone B is not in the CSS of Phone A.
D. Phone B does not have the CSS of Phone A in its partition.
E. Phone B is not registered.
F. Phone B has the incorrect CSS to dial Phone A.
