Guide · as of 2026-08-09T00:00:00.000Z
A Korean SIM splits into two regimes: prepaid (선불), which can be activated on a passport alone and works from day one, and postpaid (후불), which requires an ARC and usually a Korean bank account or credit card for billing. The dividing line that matters is not price but identity verification (본인인증): a number registered to a passport frequently fails the SMS verification used by Korean banks, government sites, delivery apps, and ticketing — the single most reported friction point for new arrivals.
All Korean SIMs are name-registered; anonymous SIMs do not exist under the telecom real-name rules (전기통신사업법 및 전기통신사업법상 부정가입 방지 제도). Registration is against either a passport (prepaid, short-term) or an ARC (postpaid and prepaid alike once the card exists).
Prepaid (선불)
- Sold at airport counters (KT, SK, LG U+ roaming desks), convenience stores in partnership with MVNOs, and online MVNO storefronts.
- Passport-only activation for stays under 90 days; an ARC can be registered later or from the start.
- Typical structure: fixed-day passes (30/60/90-day unlimited-data SIMs aimed at tourists) or rechargeable balance plans (unverified: current per-operator pricing).
- Number portability from prepaid to postpaid is possible but requires the ARC and, at some operators, in-person conversion (unverified: per-operator conversion rules).
Postpaid (후불)
- Requires ARC; billing via Korean bank account auto-debit or Korean credit card. Some carriers accept a security deposit in lieu of credit history (unverified: current deposit amounts).
- Two channels: the three MNOs (SKT, KT, LG U+) with retail stores and contract discounts, and several dozen MVNOs (알뜰폰) reselling the same networks SIM-only, without contracts, at monthly prices commonly in the ₩10,000–40,000 range depending on data allowance (unverified: representative current plan prices).
- MVNO sign-up is predominantly online and itself requires 본인인증 or a Korean credit card plus ARC scan — another circular dependency; MVNO brands with physical desks (airport, Homeplus/emart partnerships) and MNO stores resolve it in person.
The 본인인증 problem
Korean web services verify identity through carrier-based SMS authentication (휴대폰 본인인증) operated against the subscriber registry, or through the PASS app. Verification succeeds when the name, birth date, foreigner flag, and phone subscriber record all match — in effect requiring:
- a number registered under the user’s own name (not a friend’s, not a corporate line), and
- registration keyed to the ARC identity, since services compare against the alien registration record.
Passport-registered prepaid SIMs fail this comparison at most services even though calls and data work normally. Re-registering the same number under the ARC at the carrier after alien registration fixes verification without changing the number. PASS app enrollment for foreigners requires the ARC-registered line plus, in some flows, an additional ARC authenticity check against the immigration database (unverified: current PASS foreign-user flow). Banking apps increasingly accept alternatives — certificate-based login (공동인증서/금융인증서) and in-app ARC scanning — but account opening and most first-time sign-ups still route through carrier verification.
Sequence implied by the dependencies: prepaid SIM on arrival for connectivity; ARC application; after the ARC arrives, either re-register the prepaid line or port to postpaid; then 본인인증-dependent services (banking apps, 정부24, HomeTax, Coupang payment verification) become available.