Called Party Notification | Troubleshooting H.323 Call Setup

C.

When troubleshooting H.323 call setup, the message that indicates that the called party is being notified about the call is the "ALERTING" message.

The ALERTING message is sent by the called party's endpoint to the calling party's endpoint to indicate that the called party has been located and the call is being set up. The ALERTING message may include a ringback tone or other audible signal to indicate that the called party is being notified about the call.

The other message options listed in the question are as follows:

• PROCEEDING: This message is sent by the called party's endpoint to indicate that it has received the call setup request and is processing it, but the call has not yet been established.
• CONNECT: This message is sent by the called party's endpoint to indicate that the call has been established and both parties can now communicate.
• RINGING: This message is sent by the calling party's endpoint to indicate that it is hearing ringing on the called party's endpoint, but does not necessarily mean that the called party has answered the call.

Therefore, the correct answer to the question is A. ALERTING.