The appearance of an SKT direct store in downtown Seoul. /Courtesy of News1
A notice related to the hacking incident is posted at the SKT direct store in Jung-gu, Seoul. May 12, 2025 /Courtesy of News1 © News1 Min Kyung-seok

In April, a cyber intrusion incident occurred at SK Telecom, resulting in approximately 940,000 users switching their numbers in the telecommunications market during May.

According to the Korea Telecommunications Operators Association (KTOA) on the 2nd, the number of mobile number transfers among SK Telecom, KT, LG Uplus, and mobile virtual network operators (MVNOs) in May reached 933,509, marking an increase of about 77% compared to 525,937 before the incident in March.

Typically, the number of mobile number transfers is around 500,000 per month, and it has not exceeded 600,000 in the last five years. In January, there were 494,530 transfers, and levels were similar in February and March. However, in April, following the SK Telecom hacking incident, the figure approached 700,000, and in May, it neared 1 million.

The telecommunications company that benefited the most from this incident is KT. The number of users who switched from SK Telecom to KT reached 196,685 last month, whereas the usual figure is only between 30,000 and 40,000. Since April, it has surged to 95,953.

LG Uplus also reaped benefits by attracting 158,625 customers from SK Telecom. In April, LG Uplus saw nearly double its usual level with 86,500 subscribers switching from SK Telecom.

There was also active movement to mobile virtual network operators. The number of users who transferred from SK Telecom to MVNOs reached 85,180, significantly increasing from the usual 50,000 range. In contrast, the number of transfers from KT, LG Uplus, and MVNOs to SK Telecom remained in the range of 10,000.

Before the incident in February and March, the number of users transferring from KT and LG Uplus to SK Telecom was in the 40,000 range, while those transferring from MVNOs to SK Telecom were in the 20,000 range.

SK Telecom experienced damage due to the leakage of user SIM card information in April, which led to a mass exodus of subscribers. To address this, new sign-ups were temporarily suspended with measures like free SIM card replacements, and in response, SK Telecom has been focusing on customer retention by increasing subsidies for the latest smartphone models and device upgrade support.