What is the primary function of a SIM card?

What is the primary function of a SIM card?

• A. Authenticate the handset to be used on the cellular network
• B. Store the device's photos
• C. Charge the battery
• D. Control the device's screen brightness

Answer: (A)

The SIM card’s main role is to identify and authenticate the subscriber to the cellular network. It stores the subscriber’s IMSI (International Mobile Subscriber Identity) and the authentication key, which the network uses to verify that you’re allowed to access service on that network. When the phone connects, the network challenges the SIM, and the SIM responds with a value derived from the key, proving the subscriber’s identity without exposing the key. Once authenticated, the network grants access to voice, text, and data services and can manage billing and roaming for that subscriber. The other options describe functions handled by the phone’s own storage or hardware, not the SIM card.

The SIM card’s main role is to identify and authenticate the subscriber to the cellular network. It stores the subscriber’s IMSI (International Mobile Subscriber Identity) and the authentication key, which the network uses to verify that you’re allowed to access service on that network. When the phone connects, the network challenges the SIM, and the SIM responds with a value derived from the key, proving the subscriber’s identity without exposing the key. Once authenticated, the network grants access to voice, text, and data services and can manage billing and roaming for that subscriber. The other options describe functions handled by the phone’s own storage or hardware, not the SIM card.