This article was published on the ChosunBiz RM Report website at 4:48 p.m. on Jun. 2, 2026.
Consumers, 742 in total, sued the three mobile carriers, saying they signed up for expensive 5G plans believing ads that touted "5th generation (5G) communications 20 times faster than Long Term Evolution (LTE)," but they lost in the first trial.
The ruling turned on two key points. It found that SK Telecom, KT, and LG Uplus had no contractual obligation to provide 20Gbps service based on the 28㎓ frequency to consumers, and that there was no proof that consumers subscribed to 5G because of the ads in question.
Even if an ad is subject to administrative sanctions, to lead to individual consumer damages there must be proof of a causal link between the ad and the subscription.
◇ "Signed up trusting '20 times faster 5G'"… 742 consumers sue
According to legal sources on the 4th, the Seoul Central District Court Civil Division 23 (Presiding Judge Lee Jung-jae) on the 27th of last month ruled against the plaintiffs in a lawsuit seeking restitution of unjust enrichment and damages totaling 371.5 million won filed by 742 consumers, including a person surnamed Kang, against the three carriers.
The suit was filed in Sep. 2021, early in the rollout of 5G service, when subscriber complaints were mounting. In 2019, Korea became the first in the world to commercialize 5G. The Moon Jae-in administration promoted 5G as a next-generation growth engine, and former President Moon Jae-in also said at the "5G+ strategy" announcement that "5G is 20 times faster than existing 4G." Carriers, too, pushed to sign up users with "5G 20 times faster than LTE."
But the actual service fell short of expectations. Consumers argued that if the ads were accurate, 5G should be provided at 20Gbps, but real speeds were only 656–701Mbps. That is about 3–4% of the advertised speed.
They also said the Ministry of Science and ICT allocated spectrum to the three carriers on the condition that they install 15,000 base stations for 28㎓, but only about 10% were actually installed. Consumers demanded compensation of about 500,000 won per person, saying carriers failed to properly build the 28㎓ network yet reflected the related expense in high-priced plans.
◇ Court: "No contractual duty to provide 28㎓/20Gbps"
The court did not accept this. According to the ruling obtained by ChosunBiz, the panel determined it was difficult to find that the three carriers had an obligation to install 28㎓ base stations and provide consumers with service at 20Gbps.
The panel cited the technical limits of the 28㎓ frequency. While the 28㎓ band can theoretically support ultra-high-speed communications, its propagation distance is short and it is vulnerable to obstacles. The ruling also noted that signals weaken when it rains and can be cut off even if a user simply covers a phone with a hand.
It is a frequency more suitable for special services at specific locations, such as Virtual Reality (VR), Augmented Reality (AR), and medical robots, than for nationwide networks used in everyday life by general consumers.
The court also found that the government knew these limits. Then-Minister of the Ministry of Science and ICT (MSIT) Choi Ki-young said at a National Assembly audit in Oct. 2020, "The ministry has no intention at all of providing 28㎓ service to the entire population," adding, "It will largely be used to provide B2B services."
Citing this remark, the panel said it was difficult to see 28㎓ as planned for a nationwide service for general consumers. The panel said, "It is undeniable that the defendants have an obligation to provide the plaintiffs with 5G Network services," but added, "It is difficult to go so far as to find they have a duty to install base stations using the specific 28㎓ band for everyday use and provide communications at the specific speed of 20Gbps."
It also found that neither individual contracts nor terms and conditions specified any duty to provide a 28㎓ network or 20Gbps. The claim that the expense of building a nationwide 28㎓ network was included in 5G fees and passed on to consumers was also deemed insufficiently proven.
◇ FTC penalty surcharge differs from civil damages
The court also distinguished between FTC sanctions and civil liability for damages. The FTC had earlier imposed a penalty surcharge, finding the three carriers' 5G speed ads to be false or exaggerated. The panel explained, "We cannot rule out the possibility that videos and other materials related to the 5G product at issue, which formed the basis of the FTC's determination, violated the Act on Fair Labeling and Advertising."
However, the panel held that a violation of the Act on Fair Labeling and Advertising does not automatically amount to fraudulent conduct or liability for damages under the Civil Act. To recognize civil liability, each consumer must prove that they contracted in reliance on the ad and suffered damages as a result.
In particular, the court found unproven that consumers actually signed up for 5G because they saw the ads in question. A 2022 Korea Productivity Center survey showed the largest share of respondents (31.0%) cited "to keep existing benefits" as the reason for choosing a particular mobile carrier, which the court also took into account. It also considered that considerable information on 5G speeds and limitations had been made known through government announcements and media reports.
In the end, the court found that the mere circumstance that "the FTC viewed it as an exaggerated ad" was not enough to recognize individual consumer damages or the carriers' liability to compensate.
With the first-instance ruling, the three carriers have at least temporarily eased the burden of similar lawsuits spreading. Law firm Serim, representing the consumers, is expected to decide whether to appeal after reviewing the ruling.