Reading time: 3 min
SK Telecom gained 342,000 customers through mobile number portability in January 2026, a 184.7% surge driven by rival KT Corp.’s decision to waive early termination fees following a major data breach. The mass migration marks a dramatic reversal — just eight months earlier, SK Telecom was hemorrhaging subscribers after its own cybersecurity crisis exposed personal data of 23 million users.
Record Customer Migration
Of the 342,000 users who switched to SK Telecom, 221,000 came directly from KT — nearly five times the 45,000 who made the move in December, according to data from the Korean Telecommunications Operators Association. Another 73,000 migrated from LG Uplus, the country’s third-largest carrier. LG Uplus itself emerged as a secondary beneficiary, attracting 183,000 new subscribers, including 80,000 from KT.
KT’s total net outflow reached 301,000 customers to its two main competitors. While the carrier managed to draw in 121,000 new MNP users — up 53.2% from December — the inflow was dwarfed by departures. The figures represent one of the most dramatic single-month shifts in Korea’s mature telecom market in recent years.
A Crisis That Echoes an Earlier One
The context behind these numbers is what makes the story remarkable. KT’s data breach, first reported in September 2025, resulted in unauthorized micropayments affecting thousands of customers. A government-led investigation later revealed that KT had concealed malware infections and serious vulnerabilities in its femtocell management systems. Investigators confirmed that compromised servers contained names, phone numbers, email addresses, and IMEI data. KT’s decision to waive cancellation fees from December 31 was part of a compensation package — and it opened the floodgates.
But SK Telecom is no stranger to this exact scenario. In April 2025, SKT suffered what its own CEO called the worst hacking incident in telecoms history, compromising SIM-related data for approximately 23 million subscribers — nearly half of South Korea’s population. At the time, around 250,000 users switched away from SKT, and the CEO warned that waiving termination fees could push that figure to 2.5 million, potentially costing the company $5 billion over three years. Monthly MNP switches across the entire market surged to 933,000 in May 2025 — a 77% increase from March. SK Telecom was fined 134.7 billion won by the Personal Information Protection Commission.
The fact that SK Telecom is now the primary beneficiary of a competitor’s data breach — barely eight months after its own — illustrates how quickly consumer memory resets in highly competitive markets. In an environment where technology is reshaping employment and consumer behavior across Asia Pacific, brand loyalty in telecoms appears to last only as long as the next headline.
Regulatory Pressure Building
Both breaches have amplified regulatory scrutiny of South Korea’s telecoms sector. The Insolvency Service-equivalent in Korea — the Personal Information Protection Commission — has imposed record fines, and lawmakers have held multiple parliamentary hearings. A class action lawsuit against SK Telecom is gathering momentum, with an online organizing community exceeding 50,000 members. KT may face similar penalties.
The broader pattern is concerning. Two of the country’s three major carriers have now suffered significant cybersecurity failures within a single year, raising fundamental questions about the state of data protection infrastructure across Korea’s telecoms industry. For a country that positions itself as a global leader in 5G and AI-powered technology deployment, the gap between ambition and basic security is hard to ignore.
What Comes Next
KT’s fee waiver program ran for two weeks from December 31, but the January data suggests momentum may carry into February. Whether further migration materializes depends on whether KT can stabilize its subscriber base and whether regulatory action introduces new dynamics. SK Telecom, already the country’s largest carrier, has significantly strengthened its market position — though it does so carrying the memory of its own crisis still fresh in the public record.
Sources: Koreatimes
