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Prepaid SIM & MVNO plans in Korea: how to sign up
Onieum Mobile is an authorized MVNO sales agent in Korea. Prepaid plans need no credit check and work even if you have unpaid bills at another carrier. This page explains who can activate online, what to prepare, which plan to pick, and how to top up. Prices include VAT and follow the official plan guide as of 8 Oct 2026.
Prices include VAT30-day basis for prepaidOfficial sign-up screen prevails
Cheapest12,100 KRW
Recommended39,600 KRW / 30 days
SIM card5,500–8,800 KRW
Consultation08:00–22:00 (Korean)
1. Can you activate online?
Online
Self-activation (about 15 minutes)
- Age 19 or older, in your own name
- Korean resident registration card or driver's license, or an Alien Registration Card (ARC)
- A Korean simple-authentication app in your name: Kakao, Toss, PASS, Shinhan or KB
- Face verification with your ID (bright place, camera on)
- A SIM for the network you choose (see below)
- Hours: new line 08:00–21:50 · number porting 10:00–19:50
Visit
Visit a partner center
- Passport only, no ARC, or no Korean authentication app → visit a center
- Under 19 → visit with a legal guardian
- Bring your passport or ARC. The exact address is sent after your booking is confirmed.
- 77 partner centers nationwide
The sign-up screens and the booking form are in Korean. If you text us on KakaoTalk, a translation app works well; we reply in Korean.
2. Pick a plan
Prepaid: pay first, no credit check, cannot use carrier micro-payments. Postpaid (MVNO): billed next month, may be restricted if you have unpaid bills at another Korean carrier.
| Plan | Network | Price | Data | Calls / texts | Good for |
|---|---|---|---|---|---|
| Prepaid 396 (KT) · Prepaid 396 (LG U+) Recommended | KT or LG U+ | 39,600 KRW / 30 days | 10.3 GB, then up to 3 Mbps | Domestic calls & texts included | Most people; one plan that just works |
| Prepaid 459 (KT) | KT | 45,900 KRW / 30 days | 20.3 GB, then up to 3 Mbps | Included | Heavy data users |
| 5G Prepaid 20GB+ (LG U+) | LG U+ | 46,400 KRW / 30 days | 20 GB, then up to 3 Mbps | Included | 5G phones, heavy data |
| Basic 1 (KT) · Basic 1 (LG U+) | KT or LG U+ | 12,100 KRW / 30 days | 300 MB | 50 min · 30 texts | A Korean number for verification codes, Wi-Fi users |
| Prepaid 396 International (LG U+) | LG U+ | 48,400 KRW / 30 days | 300 MB, then up to 3 Mbps | Included + 20 min/day international | Frequent international calls |
| Postpaid MVNO plans | KT or LG U+ | from 17,900 KRW / month | 7 GB – 100 GB | Included | No unpaid bills elsewhere; partner perks (Daiso, Naver Pay, Coupang, Olive Young, Millie, CU) |
- The 10.3 GB (Prepaid 396) and 20.3 GB (Prepaid 459) apply when you activate on that plan. If you switch to it from another plan later, only 300 MB applies.
- "Then up to 3 Mbps" means you keep using data at reduced speed after the allowance — messaging, maps and search stay usable.
- LG U+ prepaid lines cannot use overseas roaming. KT prepaid roaming is billed separately.
- Not sure? Try the plan finder (Korean) — pick data, calls and budget and it suggests three plans.
3. Buy the SIM for your network
A SIM for one network cannot be used on the other, and a SIM from another carrier cannot be reused. Buy the SIM first, then pick a plan on the same network.
4. Self-activation in 15 steps (summary)
The full Korean guide with screenshots is at /guide. The flow below is for a KT prepaid new line; LG U+ differs only in the SIM number step. There are also three walkthrough videos (Korean audio and subtitles) that scroll through the real screens.
- Check eligibilityAge 19+, your own ID and authentication app, a SIM on hand.
- Choose the network and buy the SIMKT Baro USIM, or Modu-ui One Chip / Gogobi for LG U+.
- Open the sign-up screen and pick the networkChoose new line or number porting.
- Start face verificationA link is sent by text; open it on the phone with a camera.
- Scan your ID and your faceBright place, remove glasses or a hat if asked.
- Simple authentication in your nameKakao, Toss, PASS, Shinhan or KB.
- Fill in the applicationName, address, and the SIM serial number printed on the card.
- Choose the planPrepaid 396 is the recommended default.
- Pre-checkThe system checks the SIM and your details.
- Pick a phone numberChoose from the list (new line) or keep yours (porting).
- SubmitReview and submit the application.
- Activation complete and confirmation callAnswer the confirmation call ("happy call") from the carrier.
- Top up today (prepaid)The first top-up must be done on the activation day.
- Insert the SIM and restart 2–3 timesIf there is no signal, check APN settings and restart again.
- Monthly top-up or auto top-upSet a reminder or enable automatic top-up so the line is not suspended.
5. Topping up a prepaid line
- First top-up on activation day. If you skip it, the line can be suspended or cancelled the next day.
- Each 30 days the plan fee is deducted from your balance. Top up before the renewal date; when the balance runs out you can only receive, then the line is suspended.
- Auto top-up charges a registered card automatically every 30 days. You can set it up on the carrier's prepaid customer page or ask us to walk you through it.
- Ways to top up include credit/debit card, bank transfer and convenience-store top-up vouchers. The exact menu names are in Korean; see step 13 and step 15 of the Korean guide for screenshots.
Frequently asked questions
Can I sign up without a Korean credit check?
Yes. Prepaid plans do not depend on unpaid bills at other carriers. You pay first (top-up) and use the service. Postpaid (MVNO) plans may be restricted if you have unpaid bills elsewhere.
Can I activate online with only a passport?
No. Online self-activation needs a Korean ID (resident registration card or driver's license) or an Alien Registration Card plus a Korean simple-authentication app in your own name. With a passport only, please book a visit to one of our 77 partner centers.
Which plan should I choose first?
Our standard recommendation is Prepaid 396 (KT or LG U+ network): 39,600 KRW per 30 days, 10.3 GB of data (then up to 3 Mbps), domestic calls and texts included. Note that the 10.3 GB applies when you activate on this plan; switching to it later gives 300 MB.
Where do I buy the SIM?
KT network: 'KT Baro USIM' (8,800 KRW) at Emart24, CU, GS25 and 7-Eleven. LG U+ network: 'Modu-ui One Chip' (8,800 KRW) at Emart24 and Baemin B-mart, or 'Gogobi USIM' (5,500 KRW) at Daiso. A SIM for one network cannot be used on the other.
What happens if I don't top up?
A prepaid line must be topped up on the day it is activated. If the balance runs out later, you can only receive for a while, then the line is suspended and may be cancelled. Set up monthly or automatic top-up to avoid this.
Need help choosing?
Call or message us (Korean). Tell us how much data you use and whether you have an ARC; we will suggest a plan and the right SIM.