Internet phones are going wireless. Internet phone vendors have merged wireless networking with voice over Internet Protocol phone service to create the Wi-Fi VoIP phone. This promising--if somewhat rough around the edges--technology brings wireless calling to Net phones.

A Wi-Fi VoIP phone is a handset that looks a lot like a cell phone, only it sends and receives audio signals via a wireless network. It works within Wi-Fi's transmission range, which isn't very far. In our tests, Wi-Fi VoIP calls abruptly disconnected whenever we ventured 70 to 100 feet from our wireless router.

But, you say, you already have a cell phone. Why should you consider a Wi-Fi VoIP phone? Well, for some callers, VoIP is a whole lot cheaper. Let's say you're on the road and dread paying those outrageous cell phone roaming charges. With your Wi-Fi VoIP phone, you simply enter a free wireless hotspot and make a call. If your VoIP calling plan provides unlimited minutes to the U.S. and Canada, your call is essentially free. If you're calling internationally, you'll pay low VoIP rates, often as little as 3 cents per minute to Europe. And with VoIP, there are no roaming charges.

Wi-Fi VoIP handsets are already available from some VoIP providers, including BroadVoice and Net2Phone, as well as from hardware retailers such as ZyXel. Siemens will sell a Wi-Fi handset later this year. Vonage, the biggest VoIP startup, plans to introduce a Wi-Fi VoIP phone before the end of the year.

The handsets are not difficult to use: If you can use a cell phone, you've got the skills necessary to work a Wi-Fi VoIP phone. To make a call, you key in a number and press Send. Calls are routed onto the public-switched phone network via your VoIP carrier. The handsets can also accept incoming calls; the phone number is likely the same as your home VoIP line.

You need to have an account with a VoIP provider, and you need to make sure that your handset works with the company's service. In most cases, the handset works as part of your existing account, and the service is included in the monthly fee you already pay. If you don't already have a VoIP account, you can sign up for service when you purchase a handset.

Initially, Wi-Fi VoIP should appeal to people calling internationally, and to travelers who want to avoid roaming fees.

'A lot of people who travel may not have robust minute plans, and they'll find this very useful,' says IDC research manager Will Stofega. He used a Wi-Fi VoIP phone during a recent trip to Montreal. 'The savings were incredible,' Stofega says.

Don't confuse a Wi-Fi VoIP handset with a cordless VoIP phone, such as the Uniden UIP1868, a 5.8-GHz unit designed for Packet8 subscribers. (Uniden makes an identical model for Vonage and other VoIP providers.) The UIP1868 includes a base station that plugs directing into a broadband connection or router, and supports up to ten cordless handsets. The difference is that a Wi-Fi VoIP phone works anywhere there's a free wireless access point, whereas the cordless handset works only near its base station.

A Work in Progress

We tested two Wi-Fi VoIP phones: the UT Starcom F1000, which we used with BroadVoice's VoIP service, and the Net2Phone VoiceLine XJ200. (We have previously reviewed Net2Phone's earlier model, the XJ100.)

Both are promising devices, but they're not ready for the mainstream. Battery life is poor: The XJ200 kept conking out after 4 to 5 hours of standby--yes, standby--time, during which we made maybe 10 to 15 minutes of calls. The F1000 did much better, with about 33 hours of standby time, but that pales in comparison to today's average cell phone, which goes days between charges.

Another tech issue needs to be addressed: call handoffs from one wireless access point to another. If you move from one hotspot to another, your call gets dropped.

'You can't roam between access points,' acknowledges Net2Phone spokesperson Sarah Hofstetter.

Furthermore, Wi-Fi VoIP phones don't work in fee-based, password-protected hotspots, such as a McDonald's or Starbucks that offers wireless access. For a list of wireless hotspots worldwide (free and fee), go to PCWorld.com's Hotspot Finder.

Setup may be tricky for Wi-Fi novices too. You'll need to know whether your wireless LAN uses encryption, and if so, what kind (64-bit or 128-bit). In addition, you'll have to input your LAN's security code into the phone, a task that allows the handset to run on your network.

Net2Phone VoiceLine XJ200

At first glance, Net2Phone's slim Wi-Fi handset looks like your average cell phone. At 5 inches long, it easily fits in a coat pocket or handbag. Its 112-by-64-pixel LCD is backlit a cool shade of blue and is easy to read. The phone includes all the features you'd want--voice mail, caller ID, call forwarding, and call blocking--and its $159 price is reasonable. Then again, if you want a combo camera phone/MP3 player, look elsewhere.

Our main gripe is the XJ200's battery life, which at less than 5 hours is way too short. We found ourselves recharging the phone daily; in fact, we even reserved a spot on our strip outlet for the XJ200's AC adapter. That said, the phone looks good, and its audio quality rivals that of a comparably priced cell handset.

UT Starcom F1000

This handset, which we received from VoIP service provider BroadVoice, costs $100 (after $40 rebate) and easily surpasses the XJ200 in battery life, lasting 33 standby hours in our tests. It's slim like the XJ200 (only three-quarters of an inch thick) and only 4 inches long. It's downright petite: too petite, actually. We had to use the tips of our fingernails to press the tiny number keys.

The F1000 also supports voice mail, caller ID, and other essentials. Its screen controls are fairly intuitive, the orange-backlit LCD was bright and easy to read, and audio quality was as good as the XJ200's.

Our biggest complaint wasn't with the F1000, but with BroadVoice's VoIP phone service. Audio quality was terrible whenever we downloaded streaming video on our PC. Words were garbled and sentences were clipped. By comparison, Net2Phone's quality stayed the same during video streams.

Our advice: Save your money for the next generation of dual-mode cell/Wi-Fi phones, which are 6 to 12 months away, according to Net2Phone's Hofstetter. These devices will provide the best of both worlds: cell and Wi-FI VoIP access. We'll wait.