LG Uplus said on the 12th it will begin free USIM replacements and updates for all customers starting on the 13th. With this, following SK Telecom and KT, all three mobile carriers in Korea will provide free USIM replacements for all customers.
The measure is to apply a security enhancement that introduces random numbers into the international mobile subscriber identity (IMSI) system. An LG Uplus official said, to address security concerns related to the IMSI generation method, the company will carry out USIM replacements and updates through the end of the year.
IMSI is a 15-digit number stored on the USIM. It consists of a country code, a mobile network operator identifier, and a personal identifier, and is used to identify users on the network.
Since introducing fourth-generation mobile service (4G) in 2011 until recently, LG Uplus has issued IMSIs generated by including part of the mobile phone number. Security experts have raised concerns that this method could become a vulnerability if combined with other personal information.
The company said that while no cases of IMSI leaks or hacking have been confirmed to date, it decided to randomize IMSIs for all customers to strengthen personal data protection.
A "USIM shortage" making replacements difficult is unlikely. According to materials LG Uplus submitted to the Ministry of Science and ICT, as of the start of replacements the company has secured a total of 5.77 million units, including 3.77 million physical USIMs—2.09 million for mobile network operators (MNOs) and 1.68 million for mobile virtual network operators (MVNOs)—and 2 million eSIMs.
To reduce on-site congestion, LG Uplus has operated a store visit reservation system through the "U+one" app and its website since the 8th. Users can first check via the U+one app and the LG Uplus website whether they are subject to a USIM update or a USIM replacement. It is also possible to visit a store without a reservation, in which case users must bring an ID and their mobile phone.
Most users can switch via a software update without visiting a store. Older USIMs or some unlocked devices will likely require a visit.