POWER MANAGEMENT FOR SUBSCRIBER IDENTITY MODULE

摘要

Power management techniques for a Subscriber Identity Module (SIM) of a wireless communication device (WCD) are described. On technique makes use of a unique identifier for the SIM. In particular, a processor within the WCD reads a first unique identifier from the SIM when power is initially supplied to the WCD. During a power management cycle, the processor again receives a unique identifier from the SIM and compares the second unique identifier with the first unique identifier. This technique is useful in detecting whether the attached SIM has been exchanged. A voting process is also described to determine when to power-up and power-down the SIM. In particular, the voting process determines whether software modules running on the WCD require current or imminent access to the SIM. A modified security authorization process can be added, in which the WCD caches a user access code for authenticating the user.