ITPEC IP October 2025 Question 32

An IC card inserted into a mobile phone that records the phone number and subscriber ID — that is a SIM card (Subscriber Identity Module).

The carrier issues the SIM card when a mobile contract is made. The IC chip holds the subscriber's identity and the phone number, together with the key the network uses to authenticate the subscriber. The phone reaches the mobile network only with a valid SIM, and moving the card to another handset moves the subscription with it. An eSIM holds the same data in a chip built into the phone.

Answer (b)

Why not others:

• •(a) — describes a one-time password token, which generates a password valid once for Internet banking
• •(c) — describes a flash memory card such as an SD card, which stores music and photos
• •(d) — describes a conditional-access card (such as a B-CAS card) that lets a receiver decode scrambled digital broadcasts

Key rule: A SIM card identifies the subscriber of a mobile contract (phone number, subscriber ID, authentication key); it is not storage for content and not a password generator.

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