The market for mobile phones that can seamlessly switch to Wi-Fi will be exploited by Cisco, Siemens and startup DiVitas Networks, according to CRN’s Channel Web on Monday.

"The Holy Grail for users is being able to unify enterprise and cellular calling on a single device that seamlessly switches between the two technologies, meaning, for example, that a call initiated on the cellular network can transfer to the Wi-Fi network without interruption once a user is in range," Jennifer Follett wrote.

Now, Siemens Communications, Cisco Systems’s Linksys and a startup called DiVitas Networks have each launched products to deliver this kind of mobile phone.

"Six months ago, I had a BlackBerry and two cell phones. This drives that down to one device," said Doug Chesler, president of Federal Network Services, a VAR in Woodinville, Wash. "It’s something that everybody has been waiting for."

These kinds of phones call called Fixed-Mobile Convergence (FMC) solutions.

"You’re able to seamlessly roam from any network to any other, [even if] these networks are controlled by different entities," said Vivek Khuller, founder and CEO of DiVitas. "[We] make sure the applications you need to get your job done when you’re not at your desk are available to you equally across any of these devices, and when you roam from one network to the other, the call doesn’t drop."

Historically, some wireless carriers have felt threatened by Wi-Fi enabled phones. The Apple iPhone as currently specified can access the Web via Wi-Fi with Safari and e-mail, but not something like Skype. Voice calls are constrained to the AT&T cellular system.