Kimchi Switching From Prepaid to Postpaid in Korea: The ARC Bridge
To go from a prepaid data plan to a postpaid (후불) line that carries a real Korean 010 number, you follow one sequence: land on a data eSIM, register for your Alien Registration Card (ARC / 외국인등록증), open a Korean bank account, then convert to a KT postpaid plan. The number is issued at that conversion, not before, because Korea ties every mobile line to a verified identity and for foreigners that proof is the physical ARC. This bridge is built for long-stay residents on an F, E, or long-stay D visa. If you are visiting short term, you stop at the data eSIM and never need the rest.
Last updated: June 2026. This is general information, not legal, immigration, or banking advice; rules change, so confirm your own case with the carrier and immigration.
Who is this bridge for?
The prepaid-to-postpaid bridge is for foreigners staying long term who hold (or will hold) a residence visa and an ARC. Short-term, tourist, and visa-waiver visitors cannot convert to a Korean number and should stay on a data eSIM.
The reason is identity, not the SIM. A postpaid line is a real 010 number registered in your name, and Korea checks that name against your foreigner registration record. Long-stay categories that generally qualify include the F-series, the E-series work visas (E-1, E-2, E-5, E-7, E-9), and long-stay D-series such as the D-2 student visa and the D-10 job-seeker visa. Stay under 90 days and you never register for an ARC, so there is no line to convert. Rules and category names change, so if you are unsure your visa qualifies, ask before you buy rather than guess.
Why can’t I just get a postpaid number on arrival?
Because a postpaid line requires identity verification (본인확인), and a foreigner clears that check with a physical ARC that does not exist yet on day one. The card is issued only after you register as a foreign resident, which itself happens after you arrive.
Korea runs mobile subscriptions on a real-name, identity-verified basis, a policy overseen by the Ministry of Science and ICT (MSIT, 과학기술정보통신부). To put a line in your own name you must prove who you are, and your foreigner registration number (외국인등록번호) lives on the ARC. No card means no postpaid line, which is why the bridge starts on data and the number comes later. The registration-fact certificate (외국인등록사실확인서) — the paper saying your registration is underway — is not enough to activate a line; carriers want the physical card in hand.
What does the bridge look like, step by step?
The path runs in a fixed order: data eSIM on arrival, ARC registration, Korean bank account, then postpaid conversion. Each step opens the next, so skipping ahead does not work.
1. Land on data (day one)
Add a data eSIM before you fly and load the QR so you have internet the moment you power on at Incheon. This covers the weeks while your ARC is in process. A bridge SIM starts here too: it gives you data now and is designed to convert to postpaid later, so you buy one product instead of two.
2. Register for your ARC (within 90 days)
Anyone staying in Korea more than 90 days must complete foreign resident registration, generally within 90 days of entry, at the immigration office for your area. This is handled by the Korea Immigration Service via the HiKorea portal, under the Ministry of Justice. Bring your passport, visa documents, a photo, and proof of your address, then wait for the physical card. Book early, because appointment slots fill up in busy seasons.
3. Open a Korean bank account
Once the ARC arrives, open a Korean bank account or set up a Korean card. A postpaid plan bills monthly to a Korean payment method in your own name, so this step comes before the number. Most foreigners use a banking app such as Toss (토스), which generally needs your ARC and a Korean number in your name to finish verification.
4. Convert to KT postpaid and get your number
With the physical ARC and a Korean bank account or card, you switch from data to a monthly KT postpaid plan. Your Korean 010 number is issued at this conversion. If you bought a bridge SIM, the conversion is the moment it becomes a real line: a new Korean number is created when the postpaid switch is completed. For the full version of this sequence, including banking and verification, see our pillar guide on how to get a Korean phone number as a foreigner.
The 60-day window: what it is and why it matters
A bridge SIM runs as a 60-day data eSIM, and you convert it to a 12-month KT postpaid plan within those 60 days. The window exists because a data plan is finite and the ARC timeline is the variable you are racing.
The window solves a timing problem. The ARC commonly takes a few weeks from arrival, often two to four or more depending on the office and season, and some sources cite up to four to six weeks including the appointment wait. A 60-day data runway is sized to clear that wait with room to open a bank account and book the conversion. The job is simple: get the physical card, set up a Korean payment method, then convert before the clock runs out.
| Day range | What’s happening | Korean 010 number? |
|---|---|---|
| Day 1 | Data eSIM activates when you land and power on | No |
| Days 1–90 | Register for your ARC at immigration (deadline set by law, not the carrier) | No |
| ~Weeks 2–6 | Physical ARC arrives; open a Korean bank account or card | No |
| Within 60 days | Convert the data eSIM to a 12-month KT postpaid plan | Yes, after ARC |
| After conversion | Monthly KT postpaid line in your name | Yes |
Two clocks run at once, and people conflate them. The 90-day immigration deadline is set by law, and a phone plan cannot move it; the 60-day conversion window is the data runway on your bridge SIM. They overlap, but the immigration deadline is the one with real consequences for your stay, so treat it as the hard date.
What happens if I don’t convert in time?
If you do not convert before the 60-day window closes, the bridge SIM does not roll into a postpaid line, and a non-conversion charge applies. On Kimchi’s bridge plans this is a flat fee, currently 50 USD on the Welcome SIM and 30 USD on the Korea Starter SIM as of June 2026, and you simply do not get the 010 number.
The charge reflects the data you used without completing the contract the plan was built around, not a fee for changing your mind. To avoid it: register for your ARC early, book the immigration appointment well before week ten, and open your bank account the same week the card arrives. If an immigration backlog genuinely delays your card past the window, contact the carrier before the date passes rather than after.
Penalties at a glance
| Bridge plan | Data runway | Converts to | If you don’t convert |
|---|---|---|---|
| Kimchi Welcome SIM | 60-day 60GB data eSIM | 12-month KT postpaid | 50 USD non-conversion fee, no number |
| Korea Starter SIM | 60-day 60GB data eSIM | 12-month KT postpaid | 30 USD non-conversion fee, no number |
Prices and fees are as of June 2026 and can change; the live amount is always on the product page.
Do I need a Korean bank account before I convert?
Yes. A postpaid plan is billed monthly to a Korean payment method registered in your own name, so a Korean bank account or card has to be in place before the conversion. A foreign card or no card will not complete the switch.
This is the same identity wall that runs the rest of Korean life. Opening an account with Toss or a traditional bank generally needs your ARC plus a Korean number in your name, and the PASS app and identity check (본인확인) expect a postpaid line registered to you. The bridge handles this in the right order: ARC, then account, then conversion, so the number that lands at conversion is one your bank and the PASS app will actually accept.
Should I use a bridge SIM or two separate products?
If you know you are staying long term, a bridge SIM is usually simpler than buying a data eSIM now and shopping for a postpaid plan later, because it is one purchase tuned to the data-now, number-after-ARC sequence. If you are only visiting, skip the bridge and buy a plain data eSIM.
Here is the honest trade-off. A bridge SIM commits you to a 12-month KT postpaid plan, which is ideal if your stay clearly outlasts a year and a hassle if your plans are uncertain, so a short-course student should check the term against their visa first. Once you are fully settled, you can compare budget MVNO (알뜰폰) carriers that lease the KT, SKT, and LG U+ networks to trim your monthly cost. Most need your ARC and offer lighter English support, so they suit a second line rather than a first.
Verify it yourself (official sources)
Immigration and telecom rules change, so check the primary sources before making decisions that depend on them:
- ARC and the 90-day rule. The Korea Immigration Service and the HiKorea portal cover foreign resident registration, the deadline, and appointments. The Foreigner Information Center is reachable at 1345 inside Korea.
- Mobile identity verification. The Ministry of Science and ICT (MSIT, 과학기술정보통신부) oversees mobile subscription and real-name verification policy.
Frequently asked questions
Can I switch from prepaid to postpaid in Korea without an ARC?
No. A postpaid (후불) line in your own name needs your physical Alien Registration Card so it can pass Korea’s identity verification. Without the ARC you stay on a data eSIM, which has no Korean number, until the card arrives and you can convert.
How long do I have to convert a bridge SIM to postpaid?
Kimchi’s bridge SIMs run as a 60-day data eSIM, and you convert to a 12-month KT postpaid plan within those 60 days. The window is sized to cover the typical ARC wait plus time to open a Korean bank account, so the practical task is to register for your ARC early.
What happens if I don’t convert to postpaid in time?
If you miss the 60-day window the SIM does not become a postpaid line, no 010 number is issued, and a non-conversion fee applies, currently 50 USD on the Welcome SIM and 30 USD on the Korea Starter SIM as of June 2026. Registering for your ARC early is the way to avoid it.
Do I need a Korean bank account to convert to a postpaid plan?
Yes. A postpaid plan bills monthly to a Korean payment method in your own name, so a Korean bank account or card must be set up before you convert. Most foreigners open an account with Toss or a traditional bank once their ARC arrives.
When is my Korean phone number actually issued?
Your 010 number is created at the moment the postpaid conversion is completed, not when you first activate the data eSIM. On a bridge SIM the data runs from day one with no number, and a new Korean number is issued only when you switch to KT postpaid with your ARC and Korean payment method in place.
Does the 외국인등록사실확인서 work instead of the physical ARC?
No. The registration-fact certificate proves your registration is in progress, but converting to a postpaid line generally requires the physical Alien Registration Card. Wait for the card rather than trying to convert on the certificate.
Can a tourist convert a prepaid SIM to a postpaid Korean number?
No. Tourists and short-term or visa-waiver visitors do not register for an ARC, so there is no path to a postpaid 010 number. A data eSIM on a passport covers internet, maps, translation, and messaging for the whole trip, with nothing to convert.
Which network do Kimchi’s bridge plans convert to?
They convert to a KT postpaid plan, so your eventual 010 number runs on the KT network. The whole product is built around the data-now, number-after-ARC sequence that long-stay foreigners actually go through.
Crossing the bridge at the right time
The bridge only works in order: data first, ARC next, bank account, then the postpaid switch that creates your number. Get the immigration appointment booked early and the rest follows on schedule, well inside the 60-day window.
Staying long term on an F, E, or long-stay D visa? Start on data with a bridge plan like the Kimchi Welcome SIM or, for a clear 12-month-plus stay, the Korea Starter SIM, then convert to KT postpaid once your ARC and Korean bank account are ready so your 010 number lands at the right moment. If you want the full picture of who qualifies and how the ARC gates everything, read our guide on how to get a Korean phone number as a foreigner. Not sure your visa qualifies? Ask before you buy.