# Welcome! SIM card technology refers to the technology used in Subscriber Identity Module (SIM) cards, which are small integrated circuit (IC) cards used in mobile devices, such as smartphones, tablets, and modems, to identify and authenticate users on mobile networks. SIM cards store information, such as the user's mobile network credentials, phone number, and contact details, as well as cryptographic keys for secure communication and authentication. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://sim-cards.learn-telecom.com/welcome.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.