Lots of mobile phones can function as a modem for connecting laptops and PCs to the internet. All you need is a phone with modem circuitry enabled, a wireless data-access plan that supports using the phone as a modem, and appropriate software for your computer.

It's worth looking out for a mobile-phone carrier that'll sell monthly data plans designed for people who want to use their mobile phone as a modem (sometimes called "tethering"). If you use your phone in this manner on a standard data plan — not the carrier's phone-as-modem service - you may incur additional fees (for example, charges per kilobyte of data transferred). If your carrier doesn’t offer tech support or drivers, help is available from Howard Forums and About.com’s Mobile Office guide.

Most mobile phones connect to computers via USB cable, and many PDA phones come with the necessary cable. If yours doesn’t, you’ll have to spend about a tenner on one, or rely on a wireless Bluetooth connection.

If your mobile phone supports high-speed 3G data service, you can achieve download rates of 220 to 700 kilobits per second, comparable to slowish DSL. Remember, the EDGE service is only slightly faster than dial-up, so if 3G is not a viable option for your phone, the connection will slow to approximately 50 to 80 kbps, which is about the rate of a dial-up connection.

Any calls you receive while using your phone as a modem will go straight to voicemail. And if you place a call, your modem connection will end automatically.

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