3Com VCX V7000 Installation Manual page 91

The primary Media Gateway acts as the interface between the VCX IP
Telephony system and the external telephone network.
IP address of the primary Media Gateway
The secondary Media Gateway is an additional interface between the VCX IP
Telephony system and the external telephone network.
secondary Media Gateway, leave this entry blank.
Enter the IP address of the analog or digital media gateway that this VCX
server will use as the primary way of connecting to the Public Switched
Telephone Network (PSTN).
:
If there is no
91