Question: How can an A-Key (ANSI-41 Authentication Key) be programmed into a Subscriber Identity Module (SIM)?
Option 1: Exclusively through a direct cable connection from the mobile equipment to the SIM.
Option 2: Solely via a specific Over The Air (OTA) procedure initiated by the mobile equipment.
Option 3: Either directly by the service provider or through a specific Over The Air (OTA) procedure.
Option 4: Automatically upon SIM's first insertion into any mobile equipment.
Explanation: This is correct because the A-Key can be programmed into the SIM in two possible ways: directly by the service provider, implying a controlled and secure environment, or through a specific over-the-air procedure, allowing for remote updating. Both methods ensure the security of the A-Key without exposing it to the mobile equipment.