Here are some of the more common VoIP terms and their definitions

ATA - Analog Telephone Adapter. A device that connects between an analog telephone and an Internet connection port, and allows you to use a standard phone to make and receive VoIP calls over the Internet.

FXO - Foreign Exchange Office. A device that connects with a Central Office (CO) or PSTN analog line.

FXS - Foreign Exchange Station. A device that connects with an "end-user" device such as a telephone or fax machine.

IP PBX - IP Private Branch Exchange. A business phone system that offers advanced phone services between VoIP and PSTN networks, such as music-on-hold, automatic call-routing, voicemail, and call transfer.

IP phone - also called an Internet phone or broadband phone. An IP phone plugs into a broadband Internet connection to make and receive VoIP calls over the Internet.

PSTN - Public-Switched Telephone Network, is the commonly-known telephone network. PSTN is a ciruit-switched network.

PSTN Failover - an optional port on an IP phone or ATA device that connects to the PSTN network in case your Internet connection or electrical power goes down. This configuration requires you to have a regular telephone line and service.

SIP - Session Initiation Protocol. One of the newer, more common signaling protocols used for VoIP.

Softphone - a "software" phone on a PC that can send and receive calls over the Internet.

VoIP - Voice over Internet Protocol, which is a technology that allows you to make and receive phone calls and faxes over the Internet instead of through the telephone or cellular network.

VoIP Gateway - device that converts analog voice signals to digital IP packets for communication over an Ethernet (LAN or WAN) network.

VSP - VoIP Service Provider