{"id":82013,"date":"2026-08-17T17:28:50","date_gmt":"2026-08-17T17:28:50","guid":{"rendered":"https:\/blog\/\/blog\/alosim2024stg.wpenginepowered.com\/blog\/?p=82013"},"modified":"2026-08-17T17:28:52","modified_gmt":"2026-08-17T17:28:52","slug":"what-is-on-a-sim-card","status":"publish","type":"post","link":"https:\/\/alosim.com\/it\/blog\/what-is-on-a-sim-card\/","title":{"rendered":"What is on a SIM card?"},"content":{"rendered":"\n

In many of our junk drawers or \u201cfancy garbage\u201d drawers, there lies a neglected SIM card. But have you ever wondered what is on a SIM card?<\/strong><\/p>\n\n\n\n

They are often tossed in without a second thought as to what is actually stored on them, or whether it even matters once they\u2019re removed. So, what is on a SIM card?<\/p>\n\n\n\n

As it turns out, there actually might be more to your SIM card than you\u2019d expect.\u00a0<\/p>\n\n\n\n

What information is on a SIM card?<\/h2>\n\n\n\n

A small chip that connects your phone to your carrier’s network, a SIM card<\/a> doesn’t hold your photos or your apps, but it does carry the data essential to how your phone operates. Here’s exactly what information is stored on your SIM card. <\/p>\n\n\n\n

IMSI (International Mobile Subscriber Identity) <\/strong><\/h4>\n\n\n\n

This is the unique identifier assigned to you as a phone subscriber. A 15-digit number that tells the network who you are, the IMSI connects your device to your carrier thereby allowing calls, texts, and data to work. It never changes and is never visible to you directly.<\/p>\n\n\n\n

ICCID (Integrated Circuit Card Identifier) <\/h4>\n\n\n\n

Functionally a SIM card’s serial number, this is a unique identifier for the physical card itself (and not you as a subscriber). This is what allows carriers to track and manage individual SIMs.<\/p>\n\n\n\n

Authentication key (Ki) <\/h4>\n\n\n\n

This is a secret encryption key stored on the SIM that will verify your identity with the network whenever your phone connects. Virtually impossible to extract, this is a significant part of what makes SIM-based authentication reliably secure.<\/p>\n\n\n\n

Carrier and network <\/h4>\n\n\n\n

A SIM stores data about its network, the networks on which it’s allowed<\/a> to roam, and the settings required to connect.<\/p>\n\n\n\n

Contacts (sometimes) <\/h4>\n\n\n\n

Note that older phones did store contacts directly on the SIM card. SIM-stored contacts are limited in number and detail (think: name and phone number only). These days, most people opt to store contacts in the cloud or on the device itself.<\/p>\n\n\n\n

SMS messages (sometimes) <\/h4>\n\n\n\n

Select carriers and sometimes older devices will store a limited number of text messages directly on the SIM; however, this is increasingly uncommon.\u00a0<\/p>\n\n\n\n

What is not stored on a SIM card?<\/h2>\n\n\n\n

Contrary to what  you might expect, your SIM card actually does not store:<\/p>\n\n\n\n