LG Uplus is carrying out SIM updates and free replacements for all subscribers amid controversy over the design of its International Mobile Subscriber Identity (IMSI). About 870,000 cases have been handled in a week.

LG Uplus said on April 21 that the cumulative number of SIM update and replacement cases since April 13 stood at 868,964 as of the previous day. SIM replacements totaled 491,638 cases, while SIM updates came to 377,326 cases. The cumulative replacement rate was 5.1 percent.

On April 20, SIM replacements totaled 39,404 cases for mobile carriers, while updates numbered 24,807 cases. For budget mobile operators (MVNOs), SIM replacements totaled 14,283 cases and updates 6,753 cases. The number of customers who reserved store visits that day for SIM updates or replacements totaled 13,582. The cumulative figure was 374,245 customers, or about 3 percent of all customers.

Last month, LG Uplus drew security concerns after it became known that it reflected customers' mobile phone numbers in the IMSI generation process. IMSIs typically apply randomisation measures, but LG Uplus has designed subscriber IMSI values since 2011 to partially reflect customers' actual mobile phone numbers.