Subscriber Identity Module - Siemens A50 Service Manual

Subscriber Identity Module (SIM)
SIM is a smart card, which has a computer, and memory chip that is permanently installed in the
mobile equipment. It comes in either the size of a credit card or smaller version known as the
plug-in SIM.
The subscriber information, which includes a unique number called the International Mobile
Subscriber Identity (IMSI) is stored in the SIM card. SIM card identifies the subscriber to the
network.
To protect the SIM card from improper use, a security feature, a four digits personal identification
number (PIN), is built in. The PIN is stored in the SIM card and can be changed by the
subscriber. PIN2 is required for additional functions available with a special SIM card (Consult the
operator for more information about the PIN 2).
A code (PUK) is provided for unlocking the SIM card if the SIM card is blocked
.
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