Nextel Sim Card

The iphone does not store contacts on the sim card.

You will need to find a way to export the contacts from the previous phone to your computer.
then import them into windows address books or outlook.
Then you can sync the contact to the iphone.

You need any nextel phone and a iden USB cable. Download the iden phone book manager from: http://idenphones.motorola.com/iden/support/showSoftwareDownloads.do

Then save your address book then import into windows address book.