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Free Net calling goes beyond the PC

Start-up Skype plans to soon launch a version of its VoIP service for personal digital assistants. But the push to PDAs could have drawbacks.

Free Internet phone provider Skype plans to expand the range of devices that can use its service.

A version of Skype software for PDAs (personal digital assistants) is expected in the next few months, founder Niklas Zennstrom said in a recent interview. Currently, the software is available only for personal computers.

Skype's service lets people make unlimited free phone calls using what's known as voice over Internet Protocol (VoIP), a technology for placing calls using the Internet. The company is also working with cordless-phone makers to introduce devices that can connect with both Skype users and those on the traditional public telephone network.

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After years of slow growth, VoIP is generating significant interest among telecommunications carriers, corporations and consumers, thanks to significant improvements in quality of service.

In the past two years, the dropping price of analog telephone adapters, which turn any home phone into an Internet dialer, has enabled VoIP dialing to take place on hundreds of thousands of traditional home phones.

Skype is breaking new ground by trying to bring PDAs that can connect to the Internet into the VoIP mix, said Zennstrom, who co-authored the software the Kazaa file-sharing network uses. "It was one of the top requests from our users," he added.

But the push to PDAs could have drawbacks. To make VoIP calls, a PDA would need to have a broadband connection. For now, only a limited number of PDAs that have built-in Wi-Fi connections would be capable of making Skype calls.

Another VoIP provider that is expanding into new devices is SIPphone, which and founder

Zennstrom said Skype plans to soon add five-way conference calling. The new service, which is also free, will be available in the next version of the software.