As is the case with the majority of cell phones, the iPhone has a SIM card, which determines the device's phone number, carrier, and available features. Contacts and phone numbers are not, however, stored on the SIM card of the iPhone. Below are some useful facts about the iPhone's SIM card.

Fact 1. There are three types of SIM cards.

There are distinguishable by size. They are full-sized, Mini-SIM, and MicroSIM. The iPhone 4s uses the third type of SIM card, the MicroSIM.