Polycom RMX 1500 Administrator's Manual page 587

Chapter 17-Gateway Calls
If using the IP address of the RMX signaling host (for example,
172.22.188.22) instead of the domain name enter:
2000*3456@172.22.188.22.
To invite two participants IP: 3456 and ISDN: 9251444, enter:
2000*3456*9251444@service.polycom.com.
To invite two participants IP: 3456 and PSTN: 9251234, enter:
912000*3456**9251234@service.polycom.com.
Gateway IVR
Can be used by IP endpoints when the destination dialing string includes
the address of the MCU only. This is the same flow as the dialing method
used for ISDN/PSTN calls, however it is less recommended for IP
participants. For details, see page 17-9.
Dialing from H.323 Endpoints
Figure 17-3Dialing String and Call Flow from IP Endpoint to ISDN Endpoint
[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 the
gateway call and the IVR message.
The dialing string format is:
[MCU prefix in GK][GW Profile ID]
For example, if the MCU Prefix in the GK is 91 and the GW Profile ID is
2000 enter: 912000.
17-7