Skype is probably the most well-known VoIP service, and it runs on Windows Mobile and Pocket PC devices, but phone vendors are starting to build such features directly into new phones. Skype fighting against telcos trying to lock them out, reports the EE Times. The VoIP provider filled a petition with the Federal Communications Commission last week asking regulators to end the practice of carriers' controlling which devices and applications are used on their networks.

The idea of making a VoIP call from your mobile phone is an exciting idea, both as a technical feat and as a money saver, but will it actually take off?

Analysts group Juniper Research says that dual mode handsets are going to be big. Really big. It predicts the worldwide market for VoIP-over-Wifi handsets will grow to almost US$70 billion by 2012, but that only 2 percent of this will be WLAN-only handsets. In other words 98 per cent of Wifi phones will be dual mode handsets.

Report Author, Basharat Hamid Ashai, says that "the dual mode handset market will pick up much faster in the coming years than the single mode Wifi handset sector. The handset market is moving to a stage where no one wants to carry two or three devices in their pocket, so the ability to have a single device for all calls is a compelling proposition. Most single mode VoIP over Wifi handset manufactures are actively either designing or planning to ship dual mode phones".

The report comes as Siemens Communications and startup DiVitas Networks both announce products that let enterprise networks switch voice calls between cellular and Wifi networks, without dropping the call. DiVitas says its customers can use a Wifi hot spot, such as a at Starbucks coffee shop, reports Computerworld. Siemens doesn't support that initially but plans to in the future by certifying VPN clients on the handsets.

This all sounds impressive but, before you sell everything you own to buy stocks in dual mode handset makers, why are other analysts saying the hype around dual mode is overblown? CONTINUED