LG U+ has revealed that it will conduct a free SIM card replacement for all its customers beginning April 13, after identifying a security flaw in how the International Mobile Subscriber Identity (IMSI) is structured. This decision was made following concerns that the IMSI, which is used for subscriber identification, was linked too closely to actual telephone numbers, increasing the risk of user identification if someone knows a customer's phone number. The company affirmed that while there have been no actual security breaches reported, the potential for misuse existed, prompting them to take proactive steps to enhance security.

The telecommunications company explained that the IMSI numbers previously assigned were derived from customer phone numbers, which posed an identifiable link. This approach contrasts with SK Telecom and KT, competitors that manage IMSI values as independent, random numbers, adhering to stricter security principles. Industry experts have criticized LG U+'s method as a failure to observe basic standards of mobile telecommunications security, implying broader implications for consumer trust and regulatory scrutiny in the telecommunications market.

Moreover, LG U+ noted that they had recognized this problem after a data breach incident involving SK Telecom's SIM information last year and has been undertaking improvements since then. The move to replace SIM cards will also affect customers using budget mobile options under LG U+. By addressing this vulnerability, LG U+ aims to restore customer confidence and ensure that its security measures are in line with industry standards.