3Com V7111 - Manual (Page 10)

Abbreviations and Terminology
Each abbreviation, unless widely used, is spelled out in full when first used. Only industry-
standard terms are used throughout this manual. Hexadecimal notation is indicated by 0x
preceding the number.
Where "network" appears in this manual, it means LAN, WAN, etc. accessed via
the gateway's Ethernet interface.
FXO (F x O oreign E change ffice) is the interface replacing the analog telephone
and connects to a Public Switched Telephone Network (PSTN) line from the
Central Office (CO) or to a Private Branch Exchange (PBX). The FXO is designed
to receive line voltage and ringing current, supplied from the CO or the PBX (just
like an analog telephone). An FXO VoIP gateway interfaces between the CO/PBX
line and the Internet.
FXS (F x S oreign E change tation) is the interface replacing the Exchange (i.e., the
CO or the PBX) and connects to analog telephones, dial-up modems, and fax
machines. The FXS is designed to supply line voltage and ringing current to these
telephone devices. An FXS VoIP gateway interfaces between the analog
telephone devices and the Internet.
WARNING:
Ensure that you connect FXS ports to analog telephone or to PBX-trunk lines only
and FXO ports to Central Office (CO)/PBX lines only.
The V7111 is supplied as a sealed unit and must only be installed or serviced by
qualified service personnel.
10 3Com VCX V7111 Analog Gateway Installation Guide