Polycom RMX 1500 Administrator's Manual page 595

Polycom RMX 1500/2000/4000 Administrator's Guide
[Destination number] - the destination number as alias, IPv4 address
or ISDN/PSTN number.
The dialing string:
[MCU prefix in GK][GW Profile ID]*[Destination Number,
first participant]*[Destination Number, second
participant]**[Destination number]......*[Destination
Number, tenth participant]
For example, If the MCU Prefix in the GK is 91 and the GW Profile ID is
2000, and the destination number is 3456 (SIP) enter: 912000*3456.
To invite two participants: SIP: 3456 and ISDN: 9251444, enter:
912000*3456*9251444.
To invite two participants: SIP: 3456 and a PSTN participant whose
number is 9251234, enter: 912000*3456**9251234.
Dialing from SIP Endpoints
Figure 17-2Dialing String and Call Flow from SIP Endpoint to One, Two or Three
Endpoints
17-5