If this SIP call is initiated using delayed offer, which SIP message will UA#1 use to communicate its media capability to UA#2?

Refer to the exhibit.

If this SIP call is initiated using delayed offer, which SIP message will UA#1 use to communicate its media capability to UA#2?
A . INVITE
B . 180 Ringing
C . 200 OK
D . ACK
E . RTP Media

Answer: D

Explanation:

In the Delayed Offer process, the calling does not send its offer in the SIP INVITE Message. The callee sends the offer within the SDP fields of its answer (SIP 200 OK). The calling answers within the ACK message.