Call Setup; Call Proceeding; Alerting; Connection - 3Com MSR 50 Series Configuration Manual

Call Setup

Call Proceeding

Alerting

Connection

Capability Negotiation

Figure 682 Direct call signaling between endpoints
Endpoint 1 GateKeeper 1
ARQ(1)
ACF/ARJ(2)
Setup(3)
RAS Messages
Call Signalling Messages
Figure 683 Gatekeeper-routed call signaling
Endpoint 1 GateKeeper 1
ARQ(1)
ACF/ARJ(2)
Setup(3)
Call proceeding(4)
Alerting(10)
Connect(12)
RAS Messages
Call Signalling Messages
After receiving the ACF message from the gatekeeper, the calling endpoint sends
call signaling to set up a call. In a direct call signaling for example, the calling
endpoint first sends a call setup signaling message to the called endpoint
requesting for a connection.
After receiving the setup message, the called endpoint replies with a call
proceeding message. It may, however, not send this message.
Then the called endpoint may send an alerting message to the calling endpoint,
indicating its status, for example, ringing. The endpoint may not send this
message.
If the called endpoint accepts the call, it must send a connect message.
After the calling endpoint receives the connect message, an H.245 control
signaling channel is established to control the media session between the
endpoints. First, the two endpoints exchange information on their capabilities,
such as media format.
Endpoint 2
Call proceeding(4)
ARQ(5)
ACF/ARJ(6)
Alerting(7)
Connect(8)
Endpoint 2
Setup(5)
Call proceeding(6)
ARQ(7)
ACF/ARJ(8)
Alerting(9)
Connect(11)
H.323 Fundamentals 2359