Seoul: SK Telecom Co., South Korea's largest mobile carrier, gained more than 340,000 customers through mobile number portability (MNP) last month, as KT Corp. waived early termination fees following a major data breach, industry data showed Monday.

According to Yonhap News Agency, a total of 342,000 users switched to SK Telecom via MNP in January, marking an increase of 184.7 percent, or about 222,000 users, from the previous month. The data was compiled by the Korean Telecommunications Operators Association.

MNP, or mobile number portability, is a system that allows mobile phone subscribers to retain their existing phone numbers when changing service providers. Of the total number of new SK Telecom users, 221,000 switched from KT, compared with 45,000 in the previous month, while 73,000 users moved from LG Uplus Corp.

Additionally, LG Uplus, the country's third-largest mobile operator, attracted 183,000 users from rival companies last month, an increase of 102.3 percent from the previous month. This included 80,000 users who switched from KT.

KT experienced a 53.2 percent increase in its MNP inflow, with 121,000 users joining in January. The company implemented a program waiving cancellation fees for customers seeking to terminate their contracts early for a two-week period starting December 31. This initiative was part of KT's compensation package following a significant data breach reported in September, which led to a series of unauthorized micropayments.