Telecom user data, call-detail records and wiretap-related cooperation requests provided to investigative agencies in the second half of last year all increased from a year earlier.

The Ministry of Science and ICT said on Thursday it compiled and announced the "Status of provision of telecom user data and call-detail records and cooperation on communications restriction measures in the second half of 2025," submitted by 106 telecommunications operators.

Telecom user data refer to basic personal information on telecom service users, including names, resident registration numbers, addresses, subscription and termination dates, phone numbers and IDs. Investigative agencies and others can request it from telecom operators by official letter for swift criminal investigations, such as verifying victims of voice phishing or kidnappings.

Telecom user data provided to the prosecution, police and the National Intelligence Service in the second half of last year totalled 1,461,647 cases by phone number, up 155,523 cases, or 11.9 percent, from 1,306,124 a year earlier. By document count, the total was 534,070 cases, up 54,738, or 11.4 percent, from a year earlier.

By agency, police accounted for the most phone numbers at 1,111,134. The prosecution recorded 269,589, the National Intelligence Service 11,010, the Corruption Investigation Office for High-ranking Officials 272, and other agencies, including military investigative bodies and government ministries with special judicial police authority, 69,642.

Compared with a year earlier, police increased by 139,883 cases, the prosecution by 2,685, and other agencies by 18,742. The National Intelligence Service fell by 3,331 cases, and the anti-corruption office fell by 2,456.

Provision of call-detail records also increased. Call-detail records refer not to the contents of calls but to counterpart phone numbers and call dates and times, internet access logs and internet protocol addresses, and location-tracking data from originating base stations. Under the Protection of Communications Secrets Act, investigative agencies must obtain court authorisation to request the data from telecom operators.

In the second half of last year, provision of call-detail records totalled 349,046 cases by phone number or ID, up 90,424 cases, or 35.0 percent, from 258,622 a year earlier. By document count, the total was 189,148 cases, up 28,101, or 17.5 percent.

By agency, police recorded the most at 248,375 cases, followed by the prosecution at 87,291, the National Intelligence Service at 5,713, other agencies at 7,462 and the anti-corruption office at 205. From a year earlier, police rose by 54,342 cases, the prosecution by 29,873 and the National Intelligence Service by 3,488. The anti-corruption office fell by 138.

Communications restriction measures, which verify the contents of communications such as voice calls and emails, also increased. Such measures are limited to serious crimes including those that harm public security and crimes involving explosives, and require court authorisation.

In the second half of last year, cooperation on communications restriction measures totalled 3,042 cases by phone number, up 301 cases, or 11.0 percent, from 2,741 a year earlier. The document count was 32, up 1 from a year earlier.

By agency, the National Intelligence Service accounted for most phone numbers at 3,032. Police recorded 10. The National Intelligence Service phone-number count for communications restriction measures rose by 312 from a year earlier, while police fell by 10.