Can foreigners buy K-pop concert tickets in Korea without a Korean phone number?

Yes. NOL World, formerly Interpark Global, verifies you with a passport. You do it once by QR from your phone and it stays valid for a year.
Most Korean ticket sites verify identity by Korean mobile number, and without one you stop at that step. Interpark ran a separate site for international buyers and renamed it NOL World in December 2025; the old address now redirects there.
A Korean SIM usually does not solve it. Data-only plans carry no number, and even with a number the check wants a line registered to a real name.
Verify before ticket day, not on it. Seats go while you are still filling in the form.
Which site sells a given show varies by show. This site lists the seller on each concert page.