Polycom RMX 1500 Administrator's Manual page 594

Chapter 17-Gateway Calls
17-4
Dialing from H.323 Endpoints
Figure 17-1Dialing String and Call Flow from H.323 Endpoint to One, Two or
Three Endpoints
The calling endpoints can dial to one, two or several endpoints (up to ten)
in one dialing string.
The dialing string includes the following components:
[MCU prefix in GK] - the prefix with which the RMX is registered to
the gatekeeper.
[GW Profile ID] - The ID of the Gateway Profile to be used for routing
the call to the destination endpoint or DMA, as defined in the RMX
Gateway Profiles. It includes the parameters of the call to the destination.
* - indicates H.323, SIP or ISDN connection protocol to the destination
endpoint (followed by the appropriate destination number). Placing this
delimiter before the destination number causes the system to try to
connect the endpoint using H.323 first, then SIP and lastly ISDN
according to the selected protocols.
** - indicates a PSTN connection to the destination endpoint (followed by
the appropriate destination number).