SIM is the abbreviated form of subscriber identity module. A SIM card is a card containing a microchip which is used to identify a user on a mobile network.
A SIM card is typically inserted into a mobile phone or other mobile device. After the user enters the corresponding PIN code, the SIM card searches for a network. It is not possible to use conventional mobile networks without a SIM card.
SIM cards come in a number of different sizes, including full-size, mini, nano, and micro makes. Swiss mobile service providers normally provide their customers with SIM cards which can be adapted to mini, nano and micro sizes. Full-size SIM cards have largely been phased out, and many phones now use nano or micro SIM cards rather than the mini size.
An eSIM is an alternative to SIM cards which can be inserted into and removed from a mobile device. eSIMs are rewritable microchips which are embedded in mobile devices. With eSIMs, SIM data is written to the eSIM of a device when a mobile plan or prepaid offer is purchased, rather than prewritten to a SIM card which is inserted into a mobile device when a mobile plan is purchased.
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