Why are there multiples of each message type in the trace?

An administrator uses the Cisco Unified Real-Time Monitoring Tool to investigate recent calls on a Cisco UCM cluster. The SIP trace for an on-net. direct-media call shows two 180 Ringing and two 11 BYE messages.

Why are there multiples of each message type in the trace?
A . The source phone sends a 180 Ringing signal to the Cisco UC
B . Which sends a 180 Ringing signal to the destination phone. The same process applies to 11 BYE messages.
C . The source phone must signal to the destination phone that it is ringing, and the destination phone signals back with a 180 Ringing message. The same process applies to 11 BYE messages.
D . The calls have an MTP in the call path due to different codec support. The calls are subsequently split into two call legs.
E . The destination phone signals back to the Cisco UCM that it is ringing, and the Cisco UCM signals back to the source phone.

View Answer

Answer: A