As if VoIP wasn't applying enough pressure to land-line vendors, the technology is now going mobile - potentially affixing a thorn squarely in the side of wireless providers. Reports surfaced this week that Vonage is developing software allowing you to take calls to your Vonage number via your PDA or laptop. -

Broadband journalist Om Malik is first on the scene via his blog, noting that Vonage is working on a "softphone" solution for PDA's and laptops. In essence the software allows you to map your mobile device to your Vonage phone number and make VoIP calls on the go (for a fee). Om spoke to Vonage founder Jefferey Citron, who says the software (also available on Mac) is currently in beta. Vonage isn't alone, but the move is significant since they're one of the larger providers.

The rush is now on for chipmakers and mobile phone vendors to develop phones capable of roaming between traditional GSM or CDMA networks and Wi-Fi networks. With third generation wireless connectivity stalled and VoIP threatening to go mobile, vendors now have more than enough motivation to design such cross-network capable mobile devices.

Earlier this year at the CTIA show in Las Vegas, a company dubbed TTPCom unveiled their CDMA/802.11 chipset, which delivers a dual baseband solution on a single piece of silicon. Their "GSM.11" silicon architecture should see the market sometime in 2005, in phones that should cost less than $100.

Of course TTPCom isn't alone in positioning themselves for a new generation of hybrid phones; a handful of other more mainstream chipset manufacturers (like Nokia) are also busy tinkering in the lab. Qualcomm has been promising hybrid Wi-Fi capable phones since 2002. Mitel Networks has been pushing hard to incorporate VoIP over Wi-Fi via cell, though mobile networks need some serious upgrades if users want to keep one phone number across services.

If you're impatient for Wi-Fi VoIP over your cell, you could purchase the latest must-have geek status symbol - the Treo 600 from Palm One (something Om also comments on), plug a Wi-Fi access card into the SDIO slot, and have the best of both worlds at your finger-tips.