Before you start

An unlocked handset supporting Korean LTE and 5G bands
Passport, for an eSIM or a prepaid SIM
Alien Registration Card, for any line in your own name
A Korean bank account, for auto-debit on most monthly plans

Step-by-step

1
Buy the airport SIM knowing exactly what it is
The SKT, KT and LG U+ counters in both Incheon terminals sell prepaid lines with a real 010 number on a passport alone, active in minutes, some open around the clock. This is genuinely useful for landlords, agents and delivery drivers. It will not pass real-name verification, because a passport-registered prepaid line is not linked to your registration record.
In personWho: You, at the airport on arrival5–10 minutes
2
Or land already connected on a data eSIM
A Korea data eSIM bought before flying activates on landing and covers maps, messaging and navigation. Data-only, so no Korean number and no verification — useful as a bridge and useless as a plan. Many people run an eSIM and a prepaid line together for the first month.
Mobile appWho: You, before departureActive on landing
3
Once the ARC exists, move to a line in your own name
With the ARC and a Korean account you can sign a postpaid contract at a carrier store, or take a much cheaper MVNO plan on the same networks. Number portability lets you keep the 010 number you have been giving out. Carrier stores complete it in half an hour; MVNO sign-up is usually online and activates in a day or two.
In personWho: YouSame day, or 1–2 days for an MVNO
4
Clear real-name verification with PASS
Install the PASS verification app, which is the smoothest route for foreign residents, and use it to authenticate into banking, government portals and delivery apps. Confirm the carrier has your name recorded exactly as it appears on the ARC — mismatched hyphens, spacing or middle names are the commonest cause of failure.
Mobile appWho: YouMinutes once the line is in your name
5
Order home internet and ask what the building has
Korean fibre is fast and cheap. In Songdo, Cheongna and the newer Yeongjong towers it is fibre to the unit as standard and installation is quick. In the older mainland districts — parts of Jung-gu, Dong-gu and Bupyeong — some buildings run a shared connection from the basement, which caps your real speed regardless of the plan. Ask before signing if you work from home.
OnlineWho: YouDays to two weeks
6
Set KakaoTalk up properly
KakaoTalk is how landlords, building managers, colleagues and delivery drivers contact you. Basic messaging works on a foreign number, but payments, account recovery and identity-linked features expect a Korean 010 line in your own name.
Mobile appWho: YouSame day

Documents you’ll need

Passport, for eSIM and prepaid
Alien Registration Card, for postpaid and MVNO lines
Korean bank account details for auto-debit
An unlocked, band-compatible handset

Things most newcomers don’t know

The airport SIM counter is the single most common false start for people moving to Korea.

It is the first thing you see, it takes five minutes, it hands you a real Korean number, and it feels like the telecom problem is solved. It is not: a passport-registered prepaid line has no link to your registration record, so it fails the verification that gates banking, government portals and delivery apps. Buy it for connectivity, but plan the second step at the same time.

Source: community-reported

MVNOs resell the same three networks for a fraction of the price with identical coverage.

Korea's budget operators buy wholesale capacity from SKT, KT and LG U+, so you are on exactly the same towers at the same speeds. The trade-offs are Korean-language sign-up flows and a day or two to activate rather than instant in-store setup. Paying a flagship carrier price without needing bundled services is several times more expensive for no difference.

Source: community-reported

Name spelling must be identical across passport, ARC and carrier or verification simply fails.

The check compares strings rather than people. A middle name on the ARC but omitted at the phone shop, or a hyphen placed differently, produces a verification failure with a useless error. The phone contract is usually the last of the three to be created, so it is the one to police — read the screen at the counter before you sign anything.

Source: community-reported

In Incheon, the age of your building predicts your internet more than the plan does.

Songdo and Cheongna were wired with fibre to each unit from construction. Parts of the older mainland — Jung-gu's port district, Dong-gu, chunks of Bupyeong — have buildings from the 1970s and 1980s served by a shared basement connection, so the advertised plan speed is theoretical. Treat it as a lease-signing question if your income depends on the line.

Source: community-reported

Common mistakes to avoid

Assuming the airport prepaid SIM will pass identity verification for banking and Korean apps.
Registering the line in an employer's or a friend's name and losing control of your own number.
A name mismatch between passport, ARC and carrier record breaking PASS verification.
Letting a prepaid number lapse and losing the line every verification is tied to.
Signing a lease in an older mainland building without asking what internet reaches the unit.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.