If a cell phone user receives a message that their SIM card registration failed, it means that either their cell phone service is not activated or that the SIM card is not correctly installed in the phone. It is also possible that the SIM card is defective.
Customers should contact their service provider to ensure that their service is activated and that all payments are current. Next customers should check to ensure that the SIM card is properly installed. This process varies based on the model of phone. Customers should refer to the manual to learn how to locate the SIM card, which may be located on the side of the phone or under the battery. If the SIM card is properly installed, try the SIM card in another phone, if possible. If it still does not work, it may be a defective card. Contact the service provider or the company that the SIM card was ordered from to request a replacement SIM card.
The SIM card is a microchip that identifies a phone to the service provider and encrypts and transmits messages. It also provides internal memory storage to save contact lists and saved messages. If a cell phone does not have a SIM card, it can only make emergency calls to 911.