A SIM card contains messages

SIM card

What is stored on the SIM card?

A SIM card is like a small processor with internal memory: it is used to assign the cell phone or smartphone to a cellular network. Access to the network is authorized and voice and data transmission is encrypted using the number codes stored in the SIM card. In addition, temporary network-related data can be saved on the SIM card. The phone and notebook, a memory for SMS and the last phone numbers dialed are also integrated into the SIM card.

A so-called SIM toolkit can also be used to store small programs on the SIM card, for example news services from which you can have up-to-date information sent to you. The SIM toolkit can also be used to top up or query the prepaid credit. The plus point for such small programs that are stored directly on the SIM card is that they can be used regardless of the mobile phone used. This is because the SIM card can also be used in a new mobile phone without any apparent change in functionality. Manufacturers are now working on SIM cards that have a particularly large storage space - similar to the SD card in digital cameras. This memory could then be used for music, pictures or other documents, for example.

SIM cards also age

The ravages of time also gnaw on SIM cards: They do not have an unlimited lifespan, because every time the SIM card registers in the cellular network, it "ages". Most manufacturers say the lifespan is around 100,000 such authentication processes. Some SIM cards have a kind of lifespan counter inside that reacts to every switch on and off. When the counter reaches zero, the card is automatically deactivated.

Dual SIM: a mobile phone with two SIM cards

Use two SIM cards in parallel with one cell phone and thus two different tariffs, be reachable via two numbers and significantly reduce the cell phone bill - no problem thanks to dual SIM cell phones. If you have a dual SIM mobile phone, you can insert two different SIM cards at the same time. Before every call, SMS or internet access, the user can decide which of the two cards should be used.

Micro-SIM - the little sister

Since cell phones and smartphones are getting smaller and thinner, there is also a miniature version of the SIM card - the micro SIM. This version of the SIM card is only 15 x 12 millimeters in size. For comparison: a standard SIM card measures 25 x 15 millimeters. With regard to the chip, there are no significant differences, except for the internal memory. Despite the smaller format, it is around 50 percent larger. Apple's iPad was one of the first devices to use a micro SIM card.

Nano SIM

The successor to the micro-SIM is the even smaller nano-SIM, which enables smartphone manufacturers to build even flatter housings. In June 2012, Apple's design proposal was adopted as the standard. The cards are backwards compatible - older SIM cards can be cut to the format. The iPhone 5 and the Galaxy SIII work with such cards.

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