You type your number. The site says it’s wrong. You check it, retype it, try the other format with the country code, try it without. Same error.
The number is fine.
What happens when you press that button is that the Korean site asks a Korean mobile carrier whether this number belongs to a real, identified person. Your carrier is in another country. The question goes nowhere, no answer comes back, and the form gives you the only message it has, which is that something is wrong with the number.
What Korea is actually checking
The system is called 본인인증 (bon-in-injeung, “identity verification”), and it ties your phone number to a verified person. Banks use it. So do payment apps, delivery apps, domestic ticketing sites and a lot of government services. It is genuinely good infrastructure, and it is completely closed to someone who arrived last Tuesday.
Sign-up is where visitors get stuck more than anywhere else. When researchers went through what tourists complain about in Korea, authentication was the single largest category at 13.1% of everything logged, and digital problems together made up 27.8%.
Buying a Korean SIM often doesn’t help
This is the part that catches people who thought ahead.
You land, you buy a SIM at the airport, you now have a +82 number, and the sites still say no. Tourist SIMs are registered differently in the carrier’s system from a resident line. The number works for calls and data. It carries no identity, so the check comes back empty exactly as before.
The apps that ask nothing
Naver Map, Kakao Map, Papago. Install and use, no account required.
Get one of the map apps before you fly, because Google Maps will not give you directions here. There’s a law restricting detailed Korean map data from being sent to servers abroad, so Google doesn’t have what it needs. This is not a setting you can change and not a bug that gets fixed. Naver Map has the better English; Kakao is better on buses.
Tickets
Interpark Global and Weverse both take a plain email address, and you show your passport at the venue instead of a Korean ID.
Warn your bank before you buy. A sudden charge from a Korean ticketing site trips fraud rules constantly, and the seat-holding window on these sites runs about ten minutes, which is not enough time to get someone on the phone. This catches more people than the verification wall does.
Where you’re simply locked out
Baemin and Coupang Eats for food delivery. Naver Pay and Kakao Pay, which want a Korean bank account on top of the number. Melon Ticket, where some concerts ask for a resident registration number.
The only route in runs through somebody else’s identity, which is a real favour to ask and a real risk to grant. Plan around these rather than fighting them.
If you live here and it still fails
Your Alien Registration Card is newer than the carrier’s paperwork. Records take one to two weeks to catch up after issuance, and during that window your failures look identical to a tourist’s, which is why people assume their account is broken and start creating second ones.
Wait. Then try again.
For a short trip, a data-only eSIM covers maps, translation and messaging, and that is most of what you need. Just know what you’re buying. It sells you internet, and the wall this page is about stays where it is.