Given the SIP network shown in the diagram identify which three actions are initiated by the UAC (user agent client)? (Choose three)

A.
Initiates a SIP requests.

B.
Originated the BYE method to indicate call termination.

C.
Originates the ACK method to indicate that it has receives a response to its invitation.

D.
Contacts the user when a SIP invitation is receives.

E.
Returns a response on behalf of the user to the invitation originator.

Explanation:

1.4.4 SIP Invitation A successful SIP invitation consists of two requests, INVITE followed by ACK. The INVITE (Section 4.2.1) request asks thecalleeto join a particular conference or establish a two-party conversation. After thecalleehas agreed to participate in the call, the caller confirms that it has received that response by sending an ACK (Section 4.2.2) request. If the caller no longer wants to participate in the call, it sends a BYE request instead of an ACK.