What is a GSM Phone?

GSM (Global Service for Mobile Communication) is the mobile communications standard across the world, with the exception of North America where there are several platforms. In the US, GSM is available through AT&T Wireless, Cingular and T-Mobile, these are the only phones that will work outside of North America. There are two types of GSM phones available; dual band or tri-band. For international use outside of North America, a tri-band GSM phone is necessary because the US GSM standard is slightly different than the rest of the world.

When you buy a GSM phone, you'll need to sign-up with a Wireless Service Provider who will provide you with a SIM Card and wireless service for your phone. Wherever you buy the phone, be sure to ask about the calling service outside your calling area, and if it is possible to change the SIM Card on the phone to avoid roaming charges. This is called "unlocking" the phone.