(MONEY Magazine) – The newest Internet revolution has arrived. You can now make and receive phone calls via a high-speed Internet connection by subscribing to a service known as voice over Internet protocol. VOIP, for short, allows for a host of whiz-bang features--like having your voice mail sent to you via e-mail--previously impossible with traditional landline phones. Better still: For as little as $20 a month (about a third of what the average U.S. consumer spends on local and long distance) you can make unlimited calls with features such as caller ID, call forwarding and three-way calling. Thanks to its growing popularity--already, about half a million people have signed up--Verizon and Time Warner Cable have rolled out Internet phone services.

Eight months ago, I replaced my home phone with an Internet phone service from Vonage. So far, I have no plans to switch back. Sure, there are trade-offs. The quality of my Internet phone isn't quite as good as my old landline connection, and broadband service interruptions can cut off your calls. But my phone bill has been chopped in half, and that seems like a fair enough deal to me. Should you too get VOIP?

>>THE BASICS To subscribe, you must have a high-speed Internet connection. Since the broadband outlet and your telephone are directly connected, your PC doesn't have to be turned on for a Net phone to work. Nor do you need to bump a loved one offline to make a call. And no, the person you're calling needn't have VOIP or be connected to the Net to receive your call. You can also use the telephone you already have.

>>THE HOOKUP When you subscribe to VOIP, the service provider will send you a modem-like gizmo that translates your dulcet tones into bits and bytes that travel across the Internet. Hooking up a single phone to a VOIP adapter is a snap. Since the adapter must be plugged into both the phone and your broadband connection, things become tricky when you want to hook up several phones within a single household. The easiest solution is a phone with multiple cordless handsets.

>>THE TRADE-OFF The largest VOIP peddlers have a presence in all 50 states but don't have phone numbers available in every area code. (You don't want your primary phone number to have a different area code than your home calling area, since everyone from your neighbor to the pizza delivery guy would have to pay long-distance rates to reach you.) The biggest knock on Internet phones is that they're only as reliable as your broadband connection; if the latter goes down, so does your phone. As for sound quality, it's good, although I'm told my voice sometimes sounds the way overseas calls did years ago. Finally, since the phone number is not tied to any physical location, VOIP providers say they can route any 911 calls to the nearest emergency call center, but the caller would have to give the operator his or her exact address. Until sound quality and broadband reliability improve, it's wise to have a cell-phone backup. --CYBELE WEISSER