If you wish to use Internet telephony to replace or supplement your existing phone service, you need to sign up with a VoIP service provider. They will give you the necessary equipment for VoIP telephony and assign you a phone number that can be used like a regular phone number in PSTN. If you wish to use Internet telephony to replace or supplement your existing phone service, you need to sign up with a VoIP service provider. They will give you the necessary equipment for VoIP telephony and assign you a phone number that can be used like a regular phone number in PSTN.

Your VoIP equipment includes a broadband modem and an ATA (Analog Telephone Adapter) or IP phone. Both the ATA and the IP phone connect directly to the modem but the ATA allows you to use older analog phones for VoIP. No matter which device you use, it has a unique number associated with it that identifies your current IP (Internet Protocol) address. If you are constantly on the move and connect to the Internet at various locations, your VoIP provider keeps track of your current IP address which allows other people to contact you no matter where you are.

Even if you use your Internet phone from just one location, a VoIP provider is still necessary for most people. The majority of residential Internet connections have 'dynamic' IP addresses