AN INVITE transaction consists of a three-way handshake. The client transaction sends INVITE, the server transaction sends the response, and the client transaction sends an ACK, ( ).

The types of terminal faults can be summarized as: local AV faults, remote AV faults, and call and conference control problems.

Packet loss retransmission ARQ, similar to TCP's retransmission mechanism, requires the peer to resend the UDP when the UDP packet loss of the video stream is detected in the network Stream, the receiving side stores the received stream in a certain cache, and only opens the decoding after receiving the retransmitted stream.

TCs are capability exchange requests that inform the peer of the capability information ( ).

At the UDP layer, H.323 protocols fall into three broad categories, where the functions of the terminal control class are not included. ( )