Understanding SIM and eSIM
A USIM is a small chip you insert into the phone. An eSIM activates by download, with no chip.
How they differ
| USIM | eSIM | |
|---|---|---|
| Form | Physical chip | Download |
| Activation | Insert the chip | Install via QR code or app |
| Changing phones | Move the chip | Must be reissued |
| Support | Almost all phones | Recent models only |
| Dual use | Difficult | Two numbers alongside a USIM |
Steps
- Check whether your phone supports eSIM in the settings.
- Order a USIM or eSIM from a carrier or MVNO.
- Insert the USIM, or scan the QR code to install the eSIM.
- Verify your identity and activate.
- Check calls and data work.
What you need
- Passport and Alien Registration Card
- An unlocked phone (phones bought abroad need checking)
- A bank account or card in your name
Where to go
- Carrier shops and convenience stores (USIM sales)
- MVNO hub www.mvnohub.kr
- 1335 Korea Communications Commission
- 1345 · 1577-1366 interpreted advice
Questions people ask
Can I use the phone I brought from home? Yes if it is carrier-unlocked and supports Korean frequencies. Have a shop check it.
I want two numbers. If your phone supports eSIM, you can use a USIM (Korean number) plus an eSIM (home number).
I lost my USIM. Contact the carrier to suspend it and get a replacement. The chip is tied to your number and can be misused.
I'm here short term. There are prepaid USIMs and traveller eSIMs, sold at the airport or online.
Take care
Never give or sell your SIM to anyone. If a line in your name is used criminally, you carry the responsibility. Anyone offering to buy your SIM on the street is part of a criminal phone operation.
Related
mobile-phone · phone-plans · mvno-cheap · phone-verification
Source
Korea Telecommunications Operators Association www.ktoa.or.kr / As of 2026-08