RMX 2000 Administrator's Guide - Polycom Support

Chapter 15-Gateway Calls
15-2
During the connection phase, the number being dialed is displayed on the
screen of the calling endpoint.
If the call is not answered or it cannot be completed using one
communication protocol, the system will try to connect the endpoint
using the next communication protocol according to the selected
protocols in the following order: H.323, SIP and ISDN. PSTN numbers are
identified separately and are dialed immediately without trying other
connections.
If the call is busy, the system will not try to connect the endpoint using
another protocol.
If the call is not completed after trying all possible protocols, the system
displays the number that was dialed on the calling endpoint’s screen and
the reason for not completing the call. For details, see "Connection
Indications” on page 15-9.
When the call is connected, a new Gateway Session is created and added to
the ongoing Conferences list.
Dialing from H.323 Endpoints
Figure 15-1Dialing String and Call Flow from H.323 Endpoint to One, Two or
Three Endpoints