How does China Unicom receive short messages in Korea?

If it is a post-paid card of Unicom, you need to open international roaming and international long-distance functions to receive short messages abroad. Prepaid cards have international roaming and international long-distance functions by default.

International roaming charges can be found in the online business hall of China Unicom: domestic-international roaming; Or in the mobile phone business hall of China Unicom:-service-inquiry-tariff area-international, Hong Kong, Macao and Taiwan-roaming countries and tariff inquiry.