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SIM Full Form
The full form of SIM is “Subscriber Identity Module” or “Subscriber Identification Module“. SIM is an integrated circuit that securely stores International Mobile Subscriber Identity (IMSI). It is a portable memory chip that enables you to make phone calls or send text messages around the world where the subscriber’s network is available.
What is SIM card?
SIM card is commonly used in mobile phones which work on the GSM networks (CDMA phones generally do not use SIM cards.). It is portable so that users can use it with any supporting mobile phone. SIM card is a smart card that stores data for GSM cellular telephone customers. Such data includes user identity, phone numbers and locations, network authorization data, personal security keys, address books and archived text messages.
What are the sizes of SIM cards?
When the first SIM card was invented, it was roughly the size of a credit card. But the latest standard of SIM used to have a size of 15mm x 12mm. These days SIM cards come in three sizes:
- Standard SIM (15 x 25mm)
- Micro SIM (12 x 15mm)
- Nano SIM (8.8 x 12.3mm)
History
The first SIM card was created in 1991 by Munich-based smart card maker Giesecke and Devrient. This SIM was initially specified by the European Telecommunications Standards Institute. Today, SIM cards are ubiquitous, allowing more than 7 billion devices to be connected to cellular networks around the world.