SK Telecom starts the free USIM Exchange Service in Hacking scandal

SK Telecom (SKT) started a free USIM Exchange Service on April 28, 2025 to react to a serious hacking incident that affects customer information. This service is available nationwide in over 2,600 T-World stores from 10 a.m. Customers who subscribed to SKT on April 18, 2025 before midnight have justified the exchange.

In order to manage the expected influx of customers, SKT implemented a “free exchange reservation system” on the same day at 8:30 a.m. However, the situation quickly escalated to chaos when over 80,000 people were serviced in the online system and long lines were formed at T-world locations across the country.

Customers have expressed frustration about the lack of available USMs, and many reported that they had arrived in shops, just as not to find any stocks. “I got into the shop for the USIM Exchange, but finally I left empty hands,” said a customer who had not received any prior notification of the stock problems. This feeling was reproduced on various online platforms, on which users defend the disorganization and the lack of clear communication between SKT.

In order to take into account concerns about their information security, SKT also encourages customers to register for the USIM Protection -Service, which should offer similar protective advantages. However, this service also experiences delays, which further exacerbates the dissatisfaction of the customers.

On April 19, 2025, SKT confirmed that malicious code had led to the leak of some customers in the Usasim, which caused the company to take Swift measures to protect its subscribers. The Ministry of Science and ICT as well as the Korea Internet & Security Agency (Kisa) has initiated an investigation by the incident.

From now on, SKT claims to secure another 5 million by the end of May 2025 to have around 1 million USIMs. In view of the large number of subscribers – 23 million in the SKT network and an additional 1.87 million with MVNO services – there are concerns that this share does not meet the initial demand.

Shop employees have recommended the customer to subscribe to the USIM protection service while waiting for their stock exchanges. “We recommend that you register for the protection service to avoid potential damage while waiting for your new Usasim,” said an employee. Despite these measures, many customers still remain frustrated by the long waiting times and the unclear instructions that are intended during the exchange process.

As the situation unfolds, SKT is working to restore its online systems that have been overwhelmed by the high volume of the users who try to access the reservation portal. On April 28, customers who tried to connect to the T-World app or mobile website welcomed messages that indicate that the services had delays due to heavy traffic.

“We are aware of the problems and do everything to solve them as soon as possible,” said a spokesman for SKT. The company is confident that the additional USIMs that will soon arrive can relieve the current defect and improve the overall experience for their customers.

Despite the challenges, the start of the USIM Exchange service is a critical step for SKT to rebuild the trust with its customers after the hacking incident. The company has emphasized the commitment to the full responsibility for damage caused by the information leak in which it was found: “If damage occurs due to the USIM protection service, we assume 100% responsibility.” This promise is part of SK's wider strategy to assure customers that their security is a top priority.

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