SK Telecom claws back mobile subs as KT suffers

• Last year, South Korea’s KT Corp gained customers from SK Telecom following the latter’s major cybersecurity breach
• Then KT suffered its own security breach
• Now the roles are reversed, with SK Telecom picking up customers that have abandoned KT

The South Korean mobile market has had a turbulent year that has left mobile subscribers unsure about their safest cellular service option following a number of security breaches, the latest of which has seen more than 270,000 customers jump ship from KT Corp to rival mobile operators, with SK Telecom the main beneficiary. 

In September last year, KT admitted hackers were likely to have stolen subscriber information after managing to connect illegal mini base stations to the operator’s network, which resulted in a spate of fraudulent micropayments. It subsequently admitted its internal servers have also been compromised on a number of occasions – KT’s data breach woes get worse. 

The operator offered free SIM card replacements to all of its 16 million mobile subscribers (including those connected to the network via mobile virtual network operators) in an effort to appease its customers, but the damage was done and KT’s CEO Kim Young-seop took responsibility and decided to step down from his role – see KT Corp’s CEO falls on his cyber-breach sword.

Then, at the end of 2025, KT said it was waiving termination fees until the end of business on 13 January for any customers that decided to cancel their service contracts and the floodgates opened: According to the Korea JoongAng Daily, about 270,000 mobile customers opted to leave and that number could hit 300,000 in total before the offer ends. 

The main beneficiary has been market leader SK Telecom, which is believed to have picked up almost three-quarters of those that switched (including those that opted to churn to an MVNO running on SKT’s network). The remaining 25% have churned to LG Uplus. 

The irony of this situation is that the roles were reversed last year (and on a larger scale), when more than 800,000 subscribers abandoned SKT following its calamitous data breach that also led to a change of CEO, crippling costs, concessions and regulatory fines – see KT, LG Uplus make hay as SKT suffers and SKT suffers cyberbreach fallout, appoints new CEO.

- Ray Le Maistre, Editorial Director, TelecomTV