Which of the following descriptions of the above call process is correct?

Assume that T1 and T2 are two radio terminals registered under the same SC node area (SC does not enable media routing). After T1 calls T2’s number through the SIP protocol, T1 and T2 communicate.

Which of the following descriptions of the above call process is correct?
A . The call signaling interaction between T1 and T2 may or may not pass through the SC.
B . The media interaction between T1 and T2 may or may not go through SC.
C . Media interaction between T1 and T2 must go through SC:
D . The call signaling interaction between T1 and T2 must go through SC

Answer: D