Using a cell phone while travelling abroad can be expensive due to high out-of-service-area charges. Using an unlocked GSM phone and a SIM card from a local network can be a cheaper way to keep you connected with friends and family back home. The 3 Network in the United Kingdom offers mobile phone calls, texting and data usage along with free Windows Live messaging and free Skype-to-Skype calling and messaging.
Unlock your phone or purchase an unlocked mobile phone. Many European and Asian mobile phone providers operate on the international GSM frequencies, the same frequencies used by AT&T and T-Mobile in the United States. Many phones are "carrier locked" to only work on one network, but can be "unlocked" by the carrier to work on other networks. Many networks will unlock phones for free if requested. Some mobile phone manufacturers also sell unlocked GSM phones that will work on any network.
Buy a 3 UK SIM card. Network information on GSM phones is stored on a small chip, called a SIM card. Changing the SIM card changes what network a phone uses to make and receive calls and texts. A 3 UK SIM card can be purchased online at www.three.co.uk or in any 3 store in the United Kingdom.
Place the SIM in the phone. On many phones the slot for the SIM in under the battery, but it may also be in a compartment along the side of the phone. Turn the phone on with the SIM card installed and either "3" or "3UK" should appear in the carrier field on the phone's screen.
Non-GSM based mobile networks, such as the Verizon and Sprint networks in the U.S., use CDMA frequencies, which are not compatible with the 3 UK network.