The iPhone's "Contacts" application syncs with contact-management applications on your computer such as Mac OS X Address Book, Microsoft Entourage, Yahoo! Address Book, Windows Address Book and Microsoft Outlook 2003, 2007 and 2010. You can transfer contacts from your old phone to your new iPhone through these applications. Or you may transfer contacts from your old phone using the Subscriber Identity Module (SIM) card.
Attach the old phone's data cable to the bottom of the phone and connect the other end to an available USB port on your computer.
Export the contacts from your old phone to your computer's contact-management application. Refer to your old phone's user manual for directions on completing this step. The procedure for exporting the contacts varies depending on your phone's make and model.
Attach your new iPhone to the iPhone data cable and connect the other end of the data cable to an available USB port on your computer. Select your iPhone from the list of "Devices." Click the "Info" tab. Check the box to the left of "Sync Address Book Contacts." Click "Sync." iTunes will transfer the contacts to your new iPhone. iTunes indicates when it's safe to remove your iPhone from the data cable.
Remove the SIM card from your old phone.
Press the flat end of a paper clip into the small hole next to the headphone jack on your new iPhone. The SIM card tray will pop out of the iPhone. Put the SIM card from your old phone into the tray and push the tray into your iPhone.
Turn off your iPhone. Turn it back on.
Press the "Settings" icon and select "Mail, Contacts, Calendars."
Tap the "Import SIM contacts" button. The iPhone will transfer contacts from your old phone's SIM card to the new iPhone's "Contacts" application.
Do not remove the iPhone from the data cable during syncing.