Prepaid SIM Cards in Korea: What to Buy on Arrival

Why this is the first task

New arrivals hit a dependency chain: a bank account wants a Korean phone number, a postpaid phone plan wants an alien registration card, and registration wants an address that you often cannot secure without a phone.

A prepaid SIM breaks the chain, because it needs only a passport.

The order that works:

1. Prepaid SIM — day one, passport only
2. Alien registration — within 90 days of entry
3. Bank account — once you have the card
4. Postpaid MVNO or carrier plan — once you have both

Buying the prepaid SIM first costs a little more per gigabyte for a month or two, and saves a great deal of friction.

Where to buy

Airport counters (Incheon, Gimpo) SK Telecom, KT and LG U+ all operate desks in arrivals. Fastest option — you leave connected. Priced for travellers, and staff generally speak English. Good if you land late or need connectivity immediately.

Convenience stores CU, GS25 and 7-Eleven sell prepaid SIM packs. Cheaper than the airport. Activation is usually done through an app or website, which can be fiddly in Korean.

Online, collect at the airport Order before you fly and collect on arrival. Usually the best price with airport convenience. Requires planning ahead.

Carrier and MVNO shops in the city Wider choice of durations and data allowances, but Korean-language service in most branches.

What to bring: your passport. Prepaid registration is tied to identification, so the anonymous SIM familiar from some other countries is not how it works here.

What you get and what you do not

Typical packages Sold by duration — 5, 10, 30, 60, 90 days — with a data allowance and sometimes voice minutes. Data-only packages are cheaper but leave you without a callable number, which causes problems when arranging viewings or deliveries. Get a package with a number.

Extension Most can be topped up before expiry through an app or a store. Let one lapse and you generally lose the number, which is disruptive if you have already given it to a landlord or employer.

The identity verification gap This is the real limitation. Korean websites and apps verify identity through your mobile number, and prepaid lines frequently fail that check. You may find you cannot:

• Complete sign-up on Korean banking apps
• Book train tickets on the rail operator’s site
• Register on some government portals
• Use certain delivery and payment services

This is not a fault you can fix on the prepaid line. It is the main reason to move to a registered postpaid plan once you have your alien registration card.

Moving to postpaid

Once your registration card arrives, switching is worth doing promptly.

Keeping your number Number portability from prepaid to postpaid is possible in many cases but depends on the providers involved. Ask before you commit, especially if you have already circulated the number.

Where to go

• MVNO — cheapest, no contract options, but check identity verification support
• Big three carrier — most expensive, best support and most reliable verification

For someone staying a year or more who relies on Korean apps, a mainstream carrier or a carrier-affiliated MVNO removes a recurring source of friction.

Short stays If you are in Korea for a few months on a short-term status and will not register, staying on prepaid throughout is reasonable. Buy longer-duration packages, which cost less per day, and accept that some Korean services will remain unavailable.

eSIM If your handset supports it, eSIM prepaid products let you activate before you land and skip the counter entirely.