Criticism has been raised that 5G communications quality for current services remains inadequate even as discussions take place on a transition to 6G.

An analysis of a "Telecommunications Service Coverage Inspection and Quality Evaluation Report" submitted by the Ministry of Science and ICT showed the rate of overstated 5G coverage maps by the three mobile carriers fell to 0.17 percent in 2024 from 1.33 percent in 2023, then surged to 6.67 percent in 2025, according to People Power Party lawmaker Kwak Kyutaek (곽규택) of the National Assembly’s Science, ICT, Broadcasting and Communications Committee.

Coverage maps are maps provided by carriers so users can check whether they can use 5G services in a specific area. Kwak’s office pointed out that there are falsely 표시ed areas that are marked as service-available only on the map while service is not actually provided.

By contrast, the rate of overstated LTE coverage fell to 0.44 percent in 2025 from 1.94 percent in 2023, making neglect in 5G service management more evident.

5G quality on high-speed rail sections, where user inconvenience has been raised steadily, also did not improve. In 2025, the overall average fulfilment rate for required speeds on transport routes such as subways, high-speed rail and expressways was 96.05 percent, but high-speed rail sections were the lowest among all routes at 90.33 percent.

By service type, the fulfilment rate was 97.49 percent for web searches requiring 5 Mbps, but fell to 93.10 percent for short-form video viewing requiring 20 Mbps and 89.28 percent for videoconferencing requiring 45 Mbps. The fulfilment rate for high-definition streaming requiring 100 Mbps was 81.44 percent, increasing the likelihood of video buffering on trains.

Quality degradation was more pronounced on some high-speed rail sections. Sections flagged as inadequate where 5G download speeds were measured at below 12 Mbps totalled 19 in both 2024 and 2025, and the incidence rate of inadequate quality rose to 22.63 percent from 13.86 percent on an average basis for the three mobile carriers.

In particular, on the Cheonan-Asan to Osong and Osong to Gongju sections, the inadequate-quality phenomenon that appeared only at LG Uplus in 2024 spread across all three carriers in 2025, the review showed. Kwak pointed out that on high-speed rail sections carriers currently share one or two networks, which can degrade communications quality during crowded times or when weather worsens.

To improve this, the Ministry of Science and ICT has been pushing since September last year to build a "shared network 2.0" to expand facilities investment. It plans to first improve habitual low-quality sections such as the Pyeongtaek Jije section and complete the buildout across all sections by 2027.

Kwak said that even in indicators after April 2024, when the government announced completion of a nationwide network buildout, overstated coverage surged and quality deteriorated on high-speed rail sections where people travel the most. He said the government, which should manage and supervise carriers’ facilities investment and maintenance of appropriate services, effectively engaged in exaggerated advertising without proper verification.