SIMkorteissa

SIMkorteissa, often referred to as SIM cards, are compact integrated circuits that securely store the International Mobile Subscriber Identity (IMSI) number and its related key used to identify and authenticate subscribers on mobile telephony devices. The acronym SIM stands for Subscriber Identity Module. These cards are a crucial component of cellular networks, enabling devices to connect to a specific operator's network.

SIMkorteissa come in various sizes, with the smallest being the nano-SIM, followed by micro-SIM and mini-SIM. Older devices may have used the larger standard SIM. The physical card contains a microprocessor, memory, and input/output circuits. When inserted into a compatible device, such as a smartphone or tablet, the SIM card communicates with the network, verifying the user's identity and granting access to services like calls, texts, and data.

Beyond basic identification, SIMkorteissa can also store contact information, text messages, and other data, though modern smartphones typically rely on cloud storage for these. Embedded SIMs, or eSIMs, represent a newer technology where the subscriber identity is embedded directly into the device's hardware or software, eliminating the need for a physical card. This allows for easier switching between carriers and can enable more compact device designs. The functionality and security of SIMkorteissa are standardized by the European Telecommunications Standards Institute (ETSI).