The SIM card, which stands for "subscriber identity module," stores data that identifies your cell phone carrier. A SIM card also holds a small amount of other data, including contact information such as phone numbers and associated names. If you are a new iPhone user, you may want to prepare your iPhone by transferring contacts from your old phone into your iPhone. One method for transferring phone numbers is to import contacts from an old SIM card into your iPhone.
Turn off your iPhone and insert the SIM card into the SIM card slot. Using your SIM release pin or a paper clip, release the SIM card holder by pressing the pin into the small circular slot located next to the headphone jack. Place the SIM card with phone numbers into the SIM card holder and push the holder back into the iPhone. Turn your iPhone back on.
Tap the "Settings" icon on your iPhone's home page. This is a silver icon with a picture of gears on it.
Tap "Mail, Contacts and Calendars" from the "Settings" menu. This opens various options and settings, including options to import a new "Contact" list.
Scroll down to the bottom of the "Mail, Contacts, Calendars" menu. Tap "Import SIM Contacts." A popup message will appear that says "Importing SIM Contacts." At this point, the contacts from the old SIM card are imported onto your iPhone.