SK Telecom halts new signups after cyberattack, scrambles to replace SIMs

South Korea's biggest mobile carrier is not taking any new customers till they change SIM cards for those affected by the cyberattack.

In the fallout of a brutal April cyberattack, the mobile operator is halting all new signups, putting customer growth on hold.According to the company’s briefing, the customers will not be able to subscribe at 2,600 T World stores or online channels starting May 5th, as the company is concentrating on replacing SIM cards for the current customers affected by the cyberattack.

The company described the April incident as a large-scale data leak caused by malware and offered free SIM card replacements to all 25 million subscribers to protect customers from SIM cloning.

The replacement started on April 28th. Customers were invited to visit any of the T World stores or airport roaming centers to receive the card for free.

The company also announced that customers can schedule an in-person appointment through the carrier's new online reservation system, which is specifically dedicated to handling SIM replacements. If customers decide to replace the SIM card themselves, SKT will reimburse them. However, the replacement process has slowed due to limited inventory.

SK Telecom boasted an annual revenue of over $10 billion in 2024. After the cyberattack was confirmed in April, the company’s shares fell as much as 8.5%, hitting their lowest level since August last year.

SK Group is the second-largest family-run conglomerate in South Korea, only behind Samsung. With over 23 million customers representing about 50% of the nation’s market share, SK Telecom boasts its own music platform, operates several professional sports teams, and recently launched Korea’s largest AI semiconductor manufacturing company.

It also has its own strategic investment division, SKT Americas, operating out of Silicon Valley, California.

According to its website, the conglomerate operates more than 175 companies globally, including those in the Information and Communications Technology, advanced materials, biopharmaceuticals, mobility, life sciences, and electric vehicle battery sectors.