SIM card, usually known as a SIM card, functions as a tinny smart card that stores all the necessary data related to a mobile phone user's subscription.

At its core, SIM card functions as a copyright to accessing a cellular network, allowing consumers to send and receive calls. Furthermore, it similarly aids in keeping important contacts, text messages, and even in some cases network-specific data.

There are commonly three types of SIM cards present in the telecom market: standard, micro size, and nano. Each of these versions vary in physical dimensions, but produce similar functionality.

Every SIM card comes characterized by unique International Mobile Subscriber Identity (IMSI) number, which is comprised of a fixed length numeric sequence. This identifies each subscriber within the cellular network.

Moreover, each SIM card is configured with an individual Ki key, which serves for securing data exchange over the telecom network.

Talking about SIM cards' functionalities, they store information such as your contacts, service information, and security-related information. Apart from this, they allow additional services such as call forwarding, call waiting, and voicemail.

In conclusion, it becomes evident that SIM cards are crucial parts of our telecommunication services. They are like the IDs for our mobile networks, making sim information them work properly. Knowing your SIM information assists in solving issues related to your telecommunication service.

Furthermore, having knowledge about your SIM card may also help in facilitating decisions about upgrading your phone, switching service plans, and even in some cases travelling abroad.