What's An Unlocked Phone?

Simply put, an unlocked cell phone is a phone that is not electronically tied or locked into any one cell phone carrier network, like Sprint or Verizon Wireless.

Unlocked cell phones have always been alive and well in Europe and elsewhere around the world, but they are just now heating up in the U.S. market, where the terms SIM cards and indeed "unlocked" are almost foreign to most cell phoners.

But that is changing as more new cell phones are being released as triband or quadband, allowing them to be used anywhere in the world by simply purchasing and dropping in SIM (subscriber information module) cards. The SIM card contains your cell phone number and phone book.

Know Your Frequency

Before buying unlocked cell phones, here are some things to consider:

• In the U.S., SIM cards may be used only with unlocked GSM (global system for mobile communications) network phones. Wireless From AT&T and T-Mobile are the two major U.S. carriers currently providing GSM network service.
• The GSM networks in the U.S. and Canada require a handset capable of operating at 1900 MHz frequency. Most GSM networks elsewhere operate at 900 MHz and 1800 MHz. The trend is growing for cell phones capable of multiple frequencies. Triband phones work at three frequencies and Quad band phones at four, including 850 MHz.

So for the wireless globetrotting traveler, a GSM phone really makes sense because you can use one cell phone globally and benefit from international roaming. Or if you just want more handset selections, take a look at unlocked mobile phones.