Which of the following statements is false about point-to-point calls?

The statement is false because the Alerting message is part of the H.225.0 call signaling protocol (based on ITU-T Q.931), not the H.225.0 RAS (Registration, Admission, and Status) protocol. The RAS protocol is used for communication between an endpoint and a Gatekeeper (GK) for functions like registration and admission control (e.g., ARQ/ACF messages), which occurs before the Q.931 call setup phase. The Alerting message is sent by the called endpoint during the Q.931 phase to indicate that the user is being notified of the incoming call.

B. In a GK-controlled call, the called endpoint must request admission (send an ARQ) from the GK to accept the call after receiving the SETUP message.

C. In a typical call arbitrated by a Gatekeeper, the calling endpoint sends an Admission Request (ARQ), and the called endpoint also sends an ARQ, resulting in two requests.

D. The H.245 protocol requires endpoints to exchange and match their media capabilities (e.g., codecs) before opening logical channels to transmit the media streams.

1. Huawei HCIP-Video Conference V2.0 Training Material. In the "H.323 Protocol System" chapter

the detailed call flow diagrams distinguish between the RAS phase (ARQ/ACF) and the subsequent Q.931 call signaling phase

which includes the SETUP

ALERTING

and CONNECT messages. This clearly places Alerting outside of the RAS connection process.

2. ITU-T Recommendation H.225.0 (07/2006)

Call signalling protocols and media stream packetization for packet-based multimedia communication systems.

Section 7

"Call signalling procedures and message definitions

" details the Q.931-based messages

including Alerting (see section 7.6).

Section 8

"RAS signalling procedures and message definitions

" details the messages exchanged between endpoints and the Gatekeeper

such as AdmissionRequest (ARQ)

which are distinct from call signaling messages.

3. ITU-T Recommendation H.245 (01/2005)

Control protocol for multimedia communication. Section 7.3

"Logical channel signalling procedures

" specifies that the openLogicalChannel procedure is used after the capability exchange procedure (terminalCapabilitySet) has been completed to ensure media compatibility.