Republic of Korea(South Korea) assigns prefix separating numeral according to the following geographical location:
- Ø - Science, university stations, club stations
- 1 - Seoul, the capital city
- 2 - northern third (Gyeonggi-do, and Gangwon-do)
- 3 - west-central (Chungcheongnam-do, Chungcheongbuk-do)
- 4 - south-west (Jeollabuk-do, Jeolanam-do, Jeju-do)
- 5 - south east (Geongsangbuk-do, Geongsangnam-do)
- 8 - Antarctica (always HL8)
- 9 - United States military personnel in Korea(always HL9)
When Korea first opened amateur radio in 1960, call sign started with HM1AA then HM1AB, etc followed. These two letter suffix call signs exhausted in about 1979.
And also the HM prefix was re-assigned to North Korea in 1977 by ITU so all HM prefix in South Korea had to change to HL. In about 1980, HL1AAA started
to be issued then DS, 6K, etc call signs followed.
Amateurs in the HL block retain their suffix no matter which call-area they live in, for instance if HL1AAA moves to Busan, he can apply and become HL5AAA. Amateurs assigned calls other than HL do not have a unique suffix. In the case above DS1AAA who moves to Busan must use DS1AAA/5 as there may be a separate DS5AAA assigned. Thus HL prefixed call signs in Korea are considered priviledged.
Currently issued prefixes to amateur radio in Korea are HL, DS, 6K, 6L, 6M, D7, D9, etc.