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
Land connected on a data eSIM
A Korea eSIM bought before flying activates on landing and covers maps, messaging and navigation while everything else is pending. Data-only, so no Korean number and no verification — a bridge rather than a plan. It matters more here than in Seoul, because you will likely arrive at Gimhae or Incheon and travel to Ulsan by bus or train.
Mobile appWho: You, before departureActive on landing
2
Add a prepaid SIM on your passport if you need a number
Carrier stores in Samsan-dong and around the bus terminal sell prepaid lines with a real 010 number on a passport alone. Useful immediately for landlords, agents, colleagues and delivery drivers. It still will not clear real-name verification, because passport-registered prepaid lines have no link to your registration record.
In personWho: You5–10 minutes
3
Once the ARC exists, take 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 running 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
Never let an employer or agency hold the line in their name
This is the one telecom warning that matters more in an industrial city than elsewhere. A line registered to an employer, a labour agency or a colleague is not your identity, cannot be moved with you, and can be cut off when the relationship ends — taking your banking verification, your government logins and your KakaoTalk account with it. Insist on a line in your own name as soon as the ARC arrives.
In personWho: YouAs soon as the ARC issues
5
Clear verification with the PASS app
PASS is the smoothest verification route for foreign residents, and it authenticates you into banking, government services and delivery apps. Confirm the carrier holds your name exactly as it appears on the ARC — mismatched spacing, hyphens or middle names are the commonest single cause of failure.
Mobile appWho: YouMinutes once the line is in your name
6
Order home internet, or find out what your dormitory actually provides
Fibre to the unit is standard across Ulsan's apartment stock and installation is quick. Company housing and dormitories are the exception: the connection is usually shared, provided and controlled by the employer, and you generally cannot install your own. If you work remotely or need reliable video calls home, establish what the accommodation provides before accepting it.
OnlineWho: YouDays to two weeks

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

A number registered in someone else's name is a dependency you cannot see until it breaks.

It is common enough for an employer or agency to arrange a phone line for an arriving worker, and it is a bad arrangement: real-name verification binds banking, government and messaging accounts to that line, and none of it is yours if the contract ends badly. This is the single most consequential thing on this page for an industrial worker. Move the line into your own name the week the ARC arrives.

Source: community-reported

A number is not an identity — only a line registered to you personally clears verification.

Korean real-name verification checks your line against your registration record, and a passport-registered prepaid line has no such link. So you can call, text and navigate while remaining locked out of banking apps, government portals and most delivery services. Newcomers who think the number was the point spend weeks bewildered about why nothing will accept them.

Source: community-reported

MVNOs resell the same three networks at 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 the bundled services is several times the cost for no measurable difference — and over a multi-year contract that is real money.

Source: community-reported

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

The check compares strings, not people. A middle name recorded on the ARC but omitted at the phone shop, or a hyphen placed differently, produces a failure with an error message that explains nothing and takes a carrier visit to fix. The phone contract is usually the last of the three to be created, which makes it the one to get right at the counter.

Source: community-reported

Common mistakes to avoid

Letting an employer or labour agency hold your phone line in their name.
Assuming a prepaid or eSIM number will pass identity verification for banking and Korean apps.
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.
Accepting company housing without establishing what internet it provides and who controls it.

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