Subscriber Identity Module memory cards are used in most cellphones and you can identify them by their sizes. For instance, the Apple iPhone 4 uses the MicroSIM card, whereas other cellphone models use a full-size or mini-SIM card. If you have a jailbroken iPhone 4, use a third-party SIM card management tool to delete your old contacts information, and copy your phone's address book entries to your SIM memory card.
Open the application "Cydia" on your jailbroken Apple iPhone. Tap on the "Manage" tab button near the bottom of the screen. Next, tap on the "Sources" tab button. Click on the "Edit" button located near the top-right of the screen, and then click the "Add" button located near the top-left of the screen. You will be prompted to enter a new Cydia/APT URL.
Use the QWERTY virtual keyboard on your iPhone to enter the URL address "http://www.sinfuliphonerepo.com/" in the text box. Tap the "Add Source" button to download the SIManager application tool on your phone. Wait until Cydia updates sources on your iPhone. It may take several seconds for the process to finish updating your phone. Click on the "Search" tab located near the bottom of the screen. Click on "SIManager" to download and install the application tool.
Tap on the "SIManager" icon to launch the application tool. Click on the "Empty SIM" button to delete all of your existing contacts information on the SIM memory card. Click on the "OK" button to confirm the action. You can also use the "Copy iPhone to SIM," "Sort by position," "Sort by name" and "Start log creation" buttons on the application tool.
Select the "Copy iPhone to SIM" button if the SIM card on your iPhone is empty. The application tool will read all of your contacts information from the phone's memory and automatically copy it to the SIM memory card.
Click on "Write to SIM" located near the bottom right of the display screen. Wait until the application tool finishes copying all of your contacts information from your iPhone's memory to the SIM card memory. If you want to copy all of your contacts information on the SIM card to another Apple iPhone, remove the SIM card from your old phone. Then slide the card into the SIM card slot until it clicks or locks into place on the new iPhone.