Wireless VoIP Phones Can Learn A Lot from Plain Old Cell Phones

Wireless voice over IP is the latest in next-gen telecom, but it has a ways to go to provide the same capabilities and reliability as plain old cell phones.

Most telephone users can call 911 and know that emergency services can find them. If they're tethered to a wall, they can switch long-distance carriers without buying a new phone. If they're wireless, they can travel miles, or at least a few blocks, without a dropped call. VoIP--and especially wireless VoIP--doesn't provide those capabilities yet. As VoIP matures, it's moving from touting flashy convergence features to more mundane concerns such as call quality.

The star of last week's VON show for VoIP and IP communications was D-Link's DPH-540, touted as the first Wi-Fi flip phone. It looks and feels like a cell phone but works off a wireless Internet connection. And it's also among the first wireless VoIP phones to include technologies such as wireless multimedia aimed at improving call quality by prioritizing voice over data. Although it can be used from some wireless hot-spots, it's designed for those needing mobility within a home or small office.

Like most Wi-Fi phones, the new D-Link model isn't a practical business option. It doesn't give users an easy way to authenticate to public hot-spots. And like every other Wi-Fi phone, even those aimed at businesses, it doesn't support Extensible Authentication Protocol, the security standard common in enterprise Wi-Fi networks.

The greatest problem for wireless VoIP is coverage. "With a Wi-Fi network, you're stuck inside one building," says David Dean, telecommunications system engineer at Cedars-Sinai Medical Center in Los Angeles. The earliest adopters of VoIP over Wi-Fi have been hospitals, because the relatively powerful transmissions from cell phones can interfere with medical equipment. But Cedars-Sinai rejected VoIP. Dean instead installed an indoor microcell from LGC Wireless, to ensure that people's Sprint and Cingular phones could transmit at the lowest possible power. "We have a Wi-Fi network for data, but we stuck with cellular for voice because we need mobility outside," he says.The Location Problem

VoIP providers also are trying to implement E-911 technology that lets emergency responders know where someone is calling from. That's an FCC mandate for all VoIP service providers, but so far none has found a way to automatically track location. "If you're a VoIP customer, right now the state of the art is you manually type your address into a Web form," says Jon Metzler, business development director at Rosum, a startup that used the VON show to demonstrate its location-tracking technology. That means employees must update their addresses when they travel or work from home.

To fix this, VoIP providers are turning to wireless technologies, even on VoIP phones that don't use Wi-Fi. Rosum's technology, called TV-GPS, embeds a GPS receiver chip into a VoIP phone. The GPS chip can switch over to the timing signals embedded in TV channels when it fails to find enough satellites. TV transmitters are better than GPS satellites at broadcasting into buildings.

It's unlikely VoIP service providers will implement the same location-tracking technology, however, and that could create interoperability issues.

"It'll be just like cell phones," says Ken Arneson,VP at S5 Wireless, another startup that launched locator chips at the show. "You choose your carrier first, then choose a phone to work with it." S5's L-chip transmits a signal that can be picked up by receivers up to 50 miles away, which then triangulate in the same way as a cellular network. S5 estimates that a few thousand receivers will be needed to cover the entire country and plans to piggyback on existing cell towers. It already has test networks in two major cities, and VoIP phones and other devices with the chips will be available by the end of the year.Just like cell phones? VoIP piggybacking on cell towers? Who says you can't teach a new technology old tricks.