Things to prepare for using my smartphone in Korea

Originally published January 5, 2023 · Reviewed and updated June 5, 2026 · By Kimchi Mobile

Information verified as of June 2026. The device-registration and dual-SIM behavior described here is set by Korea’s telecom system (managed with the Korea Association for ICT Promotion, KAIT), and the exact handling can vary by carrier and by device. Confirm the current process on the official IMEI registration site www.imei.kr, or with your carrier. This article is general information for people bringing an overseas phone to Korea, not a formal carrier policy statement.

Are you about to travel to Korea for the first time? Or maybe you’re already living in Korea but still getting your bearings on how things work. Either way, one of the most useful tools you’ll have is your smartphone — it unlocks a lot of the small things that make daily life here easier.

If this is all new and a little overwhelming, don’t worry. Below is what to prepare so your overseas phone works smoothly on a Korean prepaid MVNO SIM.

Since January 2023, some foreign (overseas-manufactured) smartphones have had trouble activating on prepaid MVNO SIM cards in Korea. The usual cause is that the device isn’t pre-registered in Korea’s system, so the network doesn’t recognize it. The good news: this is fixable, and it’s usually a one-time step.

Check the following four things.

1. Make sure your smartphone is unlocked before you arrive in Korea.
   Many phones are still locked to the carrier that sold them. Contact your current carrier to unlock the phone so it can accept another carrier’s SIM.

2. Make sure your IMEI is registered.
   Because an overseas device usually isn’t pre-registered in Korea, you may need to register it so the network will activate your SIM. If your phone supports dual SIM, register both the IMEI 1 and IMEI 2 codes.

   You can register your IMEI yourself at www.imei.kr, or ask the Kimchi Mobile team to help.

   • www.IMEI.kr — operated by the Korea Association for ICT Promotion (KAIT, 한국정보통신진흥협회). (KAIT runs Korea’s IMEI pre-registration system; confirm on imei.kr.)
   • Find your IMEI by dialing *#06# on your phone.

3. Be careful with dual SIM / eSIM on a single device.
   On a prepaid MVNO line, the safest approach is to keep just one active SIM in the phone when you activate, and to avoid running two lines under different names on the same device.

   Here’s why. Korea’s system checks that the SIM(s) and the device match the registered owner. If a single device carries two lines under different account holders (for example, a roaming or eSIM line in one name and your new Korean prepaid SIM in another), or the device isn’t pre-registered, the network can place the line on a temporary hold — carriers call this a “device–name mismatch” suspension (DS 단말명의불일치 정지).

   This hold is temporary, not permanent. Earlier versions of this guide said the system would “suspend the Korean SIM and not activate it forever” — that is not accurate, and we’ve corrected it. In practice the hold is cleared once the device and lines are reconciled. The two common fixes are:

   • Pre-register the device’s IMEI 1 and IMEI 2 at www.imei.kr (IMEI pre-registration → agree to terms → verify identity → enter IMEI 1 / IMEI 2). After registering, reinsert the SIM; many users report the line restores automatically a few hours later (often within several hours). (Source: KAIT-operated imei.kr; carrier/MVNO support notes, e.g. eyes.co.kr FAQ.)
   • If your carrier sent a consent (MMS) link after a dual-SIM / eSIM change, open it and complete the identity verification and data-sharing consent; carriers note the hold is lifted once you do. (This step dates from the Sep 1, 2022 eSIM rollout; confirm with your carrier.)

   So you don’t need two SIMs under the same account to be safe — lines in the same name generally don’t trigger a mismatch. The hold is specifically about a device carrying lines whose ownership doesn’t match, or a device that isn’t registered yet. If you’re unsure, activate with one SIM in the phone, then add the second line afterward. Exact timing and handling can vary by carrier and device — confirm on imei.kr or with your carrier.

   Note: this mainly affects prepaid MVNO SIM cards, including Kimchi Mobile; many regular postpaid lines from the major carriers are handled differently.

4. If you use an eSIM-only device, prepare a backup phone.
   Some phones have no physical SIM tray and support eSIM only. Kimchi Mobile does not currently offer an eSIM product, so we cannot activate our SIM on an eSIM-only device — you’d need a phone that accepts a physical SIM. (Note: device line-ups change over time; check your specific model’s SIM support.)

In Korea, this device-registration and dual-SIM behavior isn’t an issue for every mobile service, but it does affect most prepaid MVNO SIM services, including Kimchi Mobile. If you’d rather skip the do-it-yourself registration entirely — especially with a dual-SIM or eSIM device — you can visit a carrier in Korea and have the line activated in person.

Information verified as of June 2026. Device registration and dual-SIM handling can change and can differ by carrier and device — confirm the current process on www.imei.kr (operated by KAIT) or with your carrier before you rely on it.

Step-by-Step Guide: Registering your IMEI at IMEI.kr for a prepaid SIM in Korea.

Published by Kimchi Mobile, a foreigner-focused prepaid mobile (MVNO) reseller in Korea. We can help register your device and activate your SIM; for the official IMEI system, see KAIT’s imei.kr.