SIM card
A SIM card is a smart card that is used in mobile phones, to identify the client. SIM stands for subscriber identity module. A SIM card has a microchip, and its use is protected by a PIN. When the phone is powered on, an international mobile subscriber identity number (IMSI) is broadcast. The microchip is also needed for some encryption and decryption. The SIM card and the device that it is used in (the mobile phone) are often referred to as the Mobile station.
SIM cards come in different sizes. Full-size SIM cards, which are about the same size as a credit card, are not used in phones anymore. Most smartphones use either micro SIM or nano SIM cards, but older ones use mini SIM.
SIM Card Media
SIM chip structure and packaging
4 by 4 millimetres (0.16 × 0.16 in) silicon chip in a SIM card which has been peeled open. Note the thin gold bonding wires, and the regular, rectangular digital memory areas.
The memory chip from a micro-SIM card without the plastic backing plate, next to a US dime, which is approx. 18 mm in diameter
X-ray image of a mini-SIM, showing the chip and connections
Embedded SIM from M2M supplier Eseye with an adapter board for evaluation in a mini-SIM socket
SIM cards of various German mobile operators
Dual SIM slots as shown on a feature phone
A GPP-branded SIM interposer used to circumvent network restrictions on carrier-locked iPhones
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