When all of your contacts and text messages are saved on your old phone's SIM card, you may not feel like transferring everything to a new phone. Fortunately, SIM cards make the process easy.
SIM cards are designed to enable users to transfer information from an old phone to a new phone with minimal effort. As long as it fits in your new phone, you can use your old SIM card in your new phone, according to AT&T.
To insert an old SIM card into a new phone, remove the battery from the phone, slide the SIM card into position and put the battery back in.
If your new phone does not have a SIM card, you won't be able to use your old SIM card with it. You can transfer contacts and other information from your old SIM card to your new phone by putting the information on a USB drive--or having a professional at a phone store do it for you, according to CNET.