You need to use a SIM card on Galaxy S21 if you want to use mobile data, receive SMS, or make voice calls through a cellular network.
This Galaxy S21 how-to guide explains everything you need to know about using a SIM card on Galaxy S21: the supported SIM card size, eSIM support, insert or change SIM cards, use two SIM cards, and check SIM card status on Galaxy S21.
This guide applies to all three Galaxy S21 models (Galaxy S21, S21+, and S21 Ultra). But in different regions or on different carriers, the mobile network features may slightly different.
What’s the supported SIM card size for Galaxy S21?
Galaxy S21 supports nano-SIM cards only (for the physical card) and eSIM (if your carrier supports it).
A nano-SIM is currently the smallest SIM card for mobile phones. Most phones released in the last few years adopted nano-SIM already.
So, you can use your existing SIM card if you migrated to Galaxy S21 from the following phones (just some examples):
- Samsung Galaxy S6, S7, S8, S9, S10, S20 and all their variants.
- Samsung Galaxy Note 5, Note 7 FE, Note 8, Note 9, Note 10, Note 10+, Note 10 Lite, Note