What does SIM card store and for how long?

A SIM card stores essential information for mobile devices, including the International Mobile Subscriber Identity (IMSI), phone numbers, and network-specific data. It also holds contacts and text messages, depending on the device and user settings. The data on a SIM card remains until it is overwritten, deleted, or the card is damaged or expired, which can be several years, depending on the user's usage and the service provider's policies.