If you’re a foreigner in Korea, the SIM decision isn’t really about data speed. It’s about one question:
“Will this phone number work for Korean online verification (PASS/SMS)?”
Because once verification works, everything gets easier: Kakao/Naver accounts, delivery apps, memberships, tickets, and sometimes even banking flows.
Official Links (Use These Only)
- KISA (official identity verification portal): https://identity.kisa.or.kr/
- KISA – Mobile phone identity verification (SMS vs PASS): https://identity.kisa.or.kr/web/main/bbs/edu_user/49
- Kakao – Prepaid phone verification note: https://cs.kakao.com/helps_html/1073210198
- Kakao – Not receiving verification code (SMS/PASS): https://cs.kakao.com/helps_html/1073210200
- SKT PASS (official): https://www.sktpass.com/
- KT PASS (official): https://fido.kt.com/ktauthIntro
- LG U+ PASS (official): https://www.lguplus.com/mobile/plan/addon/addon-pass/Z100000828
First, what “online verification” actually checks
Korean verification usually means 휴대폰 본인확인 (mobile phone identity verification). KISA explains that it’s commonly done by SMS or via the PASS app.
The key point is not the SIM type itself. The key point is whether your phone number is registered under your name in the carrier’s identity database—and whether the service you’re using accepts that line type.
Official: KISA – SMS vs PASS
So… Prepaid or Postpaid? The honest answer
Postpaid (contract plan) under your own name is usually the most reliable for PASS and verification across the widest range of services.
Prepaid can work, but some services (and sometimes certain line types) may have limitations. Even Kakao’s help center mentions prepaid phone verification as a special case, which is a good signal that prepaid behavior can vary by situation.
Official: Kakao – Prepaid phone verification
Decision Guide (choose based on your real life)
Choose POSTPAID if you need any of these:
- PASS verification to work consistently (not just “sometimes”)
- Fewer surprises on Kakao/Naver/large platforms
- Long-term living in Korea (work, school, visa life)
- Stability for services that are picky about identity matching
Choose PREPAID if you’re okay with these trade-offs:
- You’re short-term and mostly need data + local calls
- You can tolerate occasional verification failures (or using SMS instead of PASS)
- You’re willing to test verification early and switch if needed
Fix Checklist: Make Verification Work (Prepaid or Postpaid)
Step 1) Confirm the line is registered under YOUR name.
This is the #1 reason foreigners fail verification: the number is under a friend, spouse, employer, or “someone at the store.” Many services won’t verify unless the phone is in your name.
Step 2) Install PASS and turn notifications ON.
KISA explains PASS is a standard method. If SMS is delayed, some carriers/services may push verification through PASS, and notifications matter.
Official: KISA – PASS method
Step 3) If SMS codes don’t arrive, don’t keep smashing “resend” forever.
Kakao notes codes can be delayed and suggests resending; it also mentions PASS push notifications may be used. If you’re not receiving anything after a few tries, treat it as a line/provider issue (not “you typed it wrong”).
Official: Kakao – Not receiving the code
Step 4) Standardize your “official” name spelling.
Use the exact same spelling/spacing/hyphen format everywhere (carrier record → PASS → Kakao/Naver forms). Korea’s matching is often strict. “Close enough” fails.
Step 5) If you’re on prepaid and PASS fails, try SMS verification first.
KISA explicitly lists SMS and PASS as the main methods. If PASS is unstable on your line type, SMS may still work on some services, and it’s worth testing before switching plans.
Official: KISA – SMS vs PASS
Step 6) If verification keeps failing, contact the verification provider shown on-screen.
Many verification pages show the “provider/agency” at the bottom. If everything matches and it still fails, provider-side issues are real. Escalate there rather than repeating the same attempt 30 times.
Quick “symptom → likely cause → fastest fix”
Symptom: PASS works on some sites but fails on others.
Likely cause: The site has stricter acceptance rules for your line type.
Fastest fix: Try SMS on that site; if it’s still critical, consider switching to a postpaid line under your name.
Symptom: “Information does not match” even though you’re sure.
Likely cause: Name format mismatch vs carrier record (spacing/hyphen/middle name).
Fastest fix: Use the exact name format stored by your carrier and keep it consistent everywhere.
Symptom: SMS codes never arrive.
Likely cause: Delivery delay, spam filtering, or carrier/provider issue.
Fastest fix: Follow Kakao’s resend guidance, check PASS notifications, then escalate to the provider if it persists.
Official: Kakao – Not receiving the code
Practical Recommendation (If You Care About Time)
If your goal is “I want Korean apps and verification to stop ruining my day,” the highest success path is:
Postpaid plan under your name + PASS set up + consistent name spelling.
Prepaid can still be fine—but if you’re building a long-term life here, postpaid usually pays for itself in saved hours.