In order to take advantage of great savings by switching your SIM card when you travel overseas, you will need to have an unlocked GSM phone. This means your phone is GSM (Global System for Mobile communications) compatible and is “unlocked” meaning it doesn’t have any service provider, carrier or operator customization. This enables you to switch the SIM card without any worries of losing service or data. There are a couple of great resources online that take you through the process of unlocking your phone. See the links below.