Criticism has emerged that mobile carriers' 5G (fifth-generation mobile network) service quality remains inadequate.
On the 10th, People Power Party lawmaker Gwak Gyu-taek of the Science. ICT. Broadcasting. and Communications Committee analyzed the "telecom service coverage inspection and quality assessment report" submitted by the Ministry of Science and ICT and found that the overstatement rate on the three mobile carriers' 5G coverage maps was tallied at 6.67% in 2025. The 5G coverage map overstatement rate fell from 1.33% in 2023 to 0.17% in 2024 before surging.
A coverage map is a map provided by a carrier that allows users to check whether they can use 5G service in a specific area. In short, there were not a few cases where service was not actually available but the map showed the area as serviceable.
Unlike 5G, the LTE (fourth-generation mobile network) coverage overstatement rate fell from 1.94% in 2023 to 0.44% in 2025.
In particular, in 2025 the overall average rate of meeting required speeds across transportation routes such as subways, high-speed rail, and expressways was 96.05%, but high-speed rail segments were the lowest at 90.33%. By service type, the fulfillment rate for web search (5Mbps) was 97.49%, but short-form video viewing (20Mbps) was 93.10% and videoconferencing (45Mbps) was 89.28%. The fulfillment rate for high-definition streaming (100Mbps) was only 81.44%, suggesting a high likelihood of buffering when watching video on trains.
In some high-speed rail segments, the quality deterioration was more pronounced. Segments with substandard quality, where 5G download speeds measured below 12Mbps, numbered 19 in both 2024 and 2025, and the incidence of substandard quality rose from an average of 13.86% to 22.63% across the three carriers. Notably, in the Cheonan Asan–Osong and Osong–Gongju segments, substandard quality that appeared only at LG Uplus in 2024 spread across all three carriers in 2025. On high-speed rail segments, carriers currently share one or two networks, so service quality can degrade during peak usage times or in bad weather.
Gwak said, "Even as profits continue to pile up, carriers are effectively deceiving the public by focusing solely on rosy prospects for 6G, the next cash cow, rather than improving 5G quality," adding, "The government must not only continuously check that the three carriers follow through on improvements, but also make clear the responsibility for perceived quality in the 6G rollout by applying a 'invest first, charge later' principle."