Sales of mobile phones featuring both cellular and Wi-Fi capabilities will be booming by 2010, according to a recent study by market research firm In-Stat. In-Stat analysts predict that 132 million of the devices will be in use by then.

Wi-Fi, which offers wireless Ethernet connectivity over a range of a few hundred feet, is widely used by consumers to connect their PCs and certain handheld devices to the Internet. But until very recently,Wi-Fi has been absent from the world of cell phones.

More than 20 WiFi-enabled models are either already on the market or will be released soon. Some of these new phones will be products of collaborations between cellular carriers and companies that offer Voice over Internet Protocol (VoIP) services, which allow transmission of voice and data over the Internet.

Consumers could use a VoIP service when the device is within range of a Wi-Fi signal. Once out of Wi-Fi range, they could then operate the same phone using cellular technology, according to In-Stat analysts.