SIM Card Slot

The new iPhone can operate on multiple cellular bands, thanks to its dynamically switching on-board radio: various bands of the LTE cellular data standard, HSPA+, DC-HSDPA, GPRS, EDGE, CDMA-EvDO, and HSPA. Major U.S. partners for the iPhone 5 include AT&T, Sprint, and Verizon.

When you purchase a new iPhone, you can do so in one of two ways: with a cellular carrier contract or contract free. The first option lets you receive a significant discount on the phone, but you have to use your iPhone solely with that carrier for two to three years, depending on your carrier and region. Contract-free phones allow you to use any carrier's pay-as-you-go plan but are several hundred dollars more expensive up front. Either way, you'll need a carrier to talk on your iPhone and use cellular data.

Your iPhone needs a nano-SIM card to connect to a cellular provider. Without it, you won't be able to access call networks or cellular Internet, only Wi-Fi. If you sign up for a contract when you purchase your device, this SIM card comes preinstalled. You can see Apple's full list of supported spectrum bands on Apple's iPhone webpage under "Cellular and Wireless."

If you have a contract-free phone and need to install a nano-SIM--or you need to access your current nano-SIM card--you can remove it by sticking one end of a paper clip into the hole next to the SIM card slot.