The first SIM card was produced in 1991 by Giesecke & Devrient in Munich. Giesecke & Devrient sold the first 300 SIM cards to the Finnish wireless network operator Radiolinja.
The name SIM comes from the integrated circuits of the cards, which are called subscriber identity modules. SIM cards are an entirely integral part of cell phones, computers and networking in modern society. SIM cards store information required for authentication and allow a user’s phone to connect to the network. SIM cards have serial numbers and contain network information, which allows users to remove the card from one phone and install it in a new one without having to re-register the device.