A SIM card is included with each consumer phone purchase. A SIM (Subscriber Identity Module) is an integrated circuit which securely stores the service-subscriber key (IMSI) to identify a subscriber on mobile telephone device. The SIM is a removable card which can be transferred from one device to another. It is easy to install a new SIM card in your device. SIMPLY remove the back of your phone and remove the battery. Next, remove the actual SIM from any additional packaging that is with it. Now, insert the SIM card into the SIM slot on your phone with the metal contacts facing down. Now reinsert your battery and power up.