The subscriber identity module, or SIM, card is the small card in your mobile phone that provides the phone with its network ID. It is the SIM card that allows phones to be locked and unlocked for individual use and provides the network service provider with the information necessary to allow the phone to function on a network. If your phone or SIM card has been damaged or is malfunctioning, it may be necessary to retrieve the SIM card's number before support representatives can assist you in fixing the problem.
Turn off the mobile phone. This important step ensures that no data will be lost when the battery and SIM card are removed.
Open the battery compartment of the mobile phone. Carefully remove the battery to reveal the SIM card in a small compartment. It may be held down with a removable metal clip.
Gently remove the SIM card, removing the metal clip if necessary. Do not force any part of the SIM card or mobile phone. The SIM card will either slide or lift out with little force.
Check the back of the SIM card. The card's front will have a golden metal chip; avoid touching this side. The back of the card will have a 20-digit number printed on the card. This is your SIM number. Write down the number.
Replace the SIM card as you found it. Take care to replace the card facing the same way as you found it, using the small indented corner as a guide. If you are replacing the SIM card correctly you will not have to force the card. Replace the battery in the same way as you found it, ensuring the metal contacts are set flush with the phone's contact points. Again, the battery should fit comfortably when it has been placed correctly. Replace your mobile phone's battery cover. It is now safe to turn on the phone.