What is a SIM card?

About SIM cards

A SIM card is a very small circuit board that is inserted into your wireless phone when you sign up as a subscriber. The term SIM stands for Subscriber Identity Module. This card contains all the pertinent details pertaining to the account, including security information, subscriber information, plus memory for the phone’s address book.

When you save names and telephone numbers in your wireless phone, they are stored on the SIM card. If you replace or upgrade your phone with a similar phone, the SIM card information can usually be transferred to your new phone.

However, not all SIM cards are transferable. For example, if you purchase a different brand of phone and change providers, you’ll often find that your SIM card is not compatible. Therefore be sure to ensure the compatibility of your SIM card when upgrading or replacing your phone.

If you are purchasing your cell phone from a dealer, you can ask to test out your SIM card in the new phone before you complete your purchase.