South Korea has three mobile network operators: SK Telecom (SKT), KT and LG U+. In the Korean government's 2025 network quality evaluation, average 5G download speeds were almost identical at KT (1,030.25 Mbps) and SKT (1,024.5 Mbps), while LG U+ measured 865.88 Mbps. At the speeds needed for web browsing or short social media videos, however, all three met the requirement in more than 99% of measurements. For travelers, the differences show up when your phone drops from 5G to LTE, and when you are moving, for example on the KTX. This guide uses figures published by Korea's Ministry of Science and ICT (MSIT) to compare the three operators, and shows how to check which network your travel eSIM is using.
If you want your Korean connection ready before you fly, see the Coral eSIM plans for South Korea and pick the data allowance that fits your stay. The supported networks are listed on the product page.
Korea's mobile operators: three networks, and MVNOs (알뜰폰) that rent them
According to MSIT statistics (end of June 2026), South Korea has about 57.63 million mobile phone lines. They break down as follows.
| Operator | Mobile phone lines | Share |
|---|---|---|
| SK Telecom (SKT) | about 22.50 million | 39.0% |
| KT | about 13.39 million | 23.2% |
| LG U+ | about 11.24 million | 19.5% |
| MVNOs | about 10.49 million | 18.2% |
About 39.35 million lines, or 68.3% of the total, are 5G. Budget carriers, known in Korea as "알뜰폰" (MVNOs), have no radio network of their own and rent capacity from one of the three operators. By host network, about 4.56 million MVNO lines run on LG U+, about 4.05 million on KT and about 1.88 million on SKT. In other words, even with an MVNO SIM, the signal comes from SKT, KT or LG U+. How to buy a SIM locally is covered in how to buy a local SIM card in Korea.
All three Korean mobile operators run 5G on the 3.5 GHz band (n78)
All three operators use the 3.5 GHz band as their main 5G spectrum. In the 2018 spectrum auction, LG U+ received 3.42 to 3.5 GHz, KT 3.5 to 3.6 GHz and SKT 3.6 to 3.7 GHz. LG U+ initially had only 80 MHz, but the neighboring 3.40 to 3.42 GHz block was added in 2022, so all three now have 100 MHz.
These frequencies fall within the international band "n78" (3.3 to 3.8 GHz). If your phone supports n78, it can use any of the three operators' 5G as far as frequency is concerned. You can check this by looking for "n78" in the manufacturer's specification sheet.
Korean 5G mostly works together with LTE
Most Korean 5G uses NSA (non-standalone), a method that combines the 5G signal with LTE. In December 2025, MSIT stated that most operators still provide 5G mainly in NSA mode, and made a move to SA (standalone) 5G, which runs without LTE, a condition of the spectrum reallocation. KT has offered SA 5G to SA-capable devices since 2021.
Under NSA, LTE is used as part of a 5G connection, so the quality of the LTE side also affects how 5G feels. Korean LTE uses frequencies including 1.8 GHz, 2.1 GHz and 2.6 GHz, which correspond to bands 3, 1 and 7 in the international standard.
Korea mobile operator speeds: the government's 2025 evaluation
MSIT and the National Information Society Agency (NIA) measure and publish network quality by operator every year. The 2025 evaluation covered 600 locations nationwide between July and December. Measurements were taken with a Samsung Galaxy S24 Ultra, and for the first time 5G and LTE were measured at the same time.
| Metric | SKT | KT | LG U+ |
|---|---|---|---|
| 5G average download | 1,024.5 Mbps | 1,030.25 Mbps | 865.88 Mbps |
| 5G average upload | 94.56 Mbps | 78.37 Mbps | 78.72 Mbps |
| 5G latency | 18.51 ms | 19.24 ms | 27.23 ms |
| 5G share of measurements at 100 Mbps or more | 98.39% | 97.88% | 98.28% |
| LTE average download | 119.36 Mbps | 88.38 Mbps | 80.79 Mbps |
| LTE share of measurements at 45 Mbps or more | 82.16% | 72.04% | 68.45% |
On 5G, KT and SKT are nearly tied and LG U+ is somewhat slower. Yet the 5 Mbps needed for web searches and the 20 Mbps needed for short videos were met in more than 99% of measurements nationwide. As long as you are on 5G, none of the three will be too slow for maps or ride-hailing apps.
The bigger gap is on LTE. SKT's LTE averaged 119 Mbps, more than 30% faster than KT and LG U+. SKT also met the 45 Mbps needed for video calls in 82% of measurements, compared with 68% for LG U+. When you fall back from 5G to LTE, deep inside buildings or underground for example, the operator makes a more noticeable difference.
Where Korean operators differ: Seoul, the subway, the KTX and rural areas
Average 5G download speeds by location from the same evaluation:
| Location | SKT | KT | LG U+ |
|---|---|---|---|
| Seoul | 1,147.88 Mbps | 1,118.64 Mbps | 965.95 Mbps |
| Busan | 1,214.48 Mbps | 1,209.04 Mbps | 926.65 Mbps |
| Jeju | 1,056.31 Mbps | 995.86 Mbps | 839.77 Mbps |
| Subway trains | 959.91 Mbps | 952.52 Mbps | 873.58 Mbps |
| High-speed rail (KTX, SRT) | 374.53 Mbps | 381.34 Mbps | 423.16 Mbps |
| Rural areas | 623.71 Mbps | 643.86 Mbps | 584.84 Mbps |
In cities, SKT and KT are faster and LG U+ trails a little. On high-speed trains, however, LG U+ came out fastest. All three are weak on high-speed rail, where only 81.44% of measurements reached 100 Mbps. KTX sections such as Cheonan-Asan to Osong and Osong to Daejeon were listed as sections where 5G quality fell below the standard. On a day when you take the KTX from Seoul to Busan, it is safer not to plan on handling large files on board.
In some rural areas, all three operators share one 5G network
In parts of rural Korea, the three operators split the regions, each building 5G base stations in its own area and letting the others use them. This is called the shared network. SKT covers areas such as Sejong, South Chungcheong and South Gyeongsang, KT covers areas such as North Gyeongsang and Gangwon, and LG U+ covers areas such as South and North Jeolla and parts of Jeju. In these areas you end up on the same 5G network whichever operator your line uses. Outside the cities, being within coverage matters more than which operator you pick.
Which Korean operator will your travel eSIM connect to? How to check
Most travel eSIMs connect by roaming on a Korean operator's network. Which one depends on the product: some use a single operator, others support several. On the product page for Coral eSIM's South Korea plans, the supported networks shown are SKTelecom (5G) and LG Uplus (5G), as of September 26, 2026. What is shown can differ by plan, so check the entry for the plan you buy.
- Before you buy: check the supported network section on the product page for the operator names and 5G support
- Check your phone: look for n78 (5G) and bands 1, 3 and 7 (LTE) on the specification sheet. The phone must also be unlocked (how to check if your phone is unlocked)
- After you arrive: on iPhone, go to Settings, then Cellular (or Mobile Data), your travel line, then Network Selection, to see the operator you are connected to. On Android the wording varies by model, but you can check it under the SIM settings, for example "Network operators"
- If it is slow: if your plan supports more than one operator, turn off automatic selection and choose another operator manually. When you are on LTE, switching to SKT may help
- Leave the APN alone: it is normally set up when you install the eSIM. Change it only if your instructions tell you to (eSIM APN settings)
For installing the eSIM and switching lines after you land, see the Korea eSIM setup guide. If speeds are poor, see what to do when your eSIM is slow. You can check each plan's supported networks on the Coral eSIM South Korea plans page.
Korea mobile operators: frequently asked questions
Which Korean mobile operator is the fastest?
In the government's 2025 quality evaluation, average 5G download speeds were almost the same at KT (1,030.25 Mbps) and SKT (1,024.5 Mbps), with LG U+ at 865.88 Mbps. On LTE, SKT led clearly at 119.36 Mbps, well ahead of KT and LG U+. On high-speed trains alone, LG U+ was the fastest.
Which operator should my travel eSIM connect to?
Prioritize 5G support first. On 5G, all three operators are fast enough for everyday use. When you fall back to LTE, SKT has the advantage. You can see which operator a plan connects to in the supported network section of the product page.
Are Korean MVNOs (알뜰폰) slower than the three main operators?
MVNOs have no radio network of their own and rent capacity from SKT, KT or LG U+. The government's quality evaluation covers the three operators' networks, and results for individual MVNOs are not published. Checking which host network an MVNO uses is a useful guide.
Will my phone from home work on Korean 5G?
All three Korean operators provide 5G on the 3.5 GHz band (band n78). If your phone supports n78, it can use Korean 5G as far as frequency is concerned. Whether you actually get a 5G connection depends on whether your plan supports 5G in Korea.
How can I check or change the operator I am connected to?
On iPhone, go to Settings, then Cellular, your travel line, then Network Selection. If your plan supports more than one operator, you can turn off automatic selection and choose another operator from the list. On Android the wording depends on the model; look in the SIM settings, for example under "Network operators".
In Korea, choose your eSIM by 5G support first, not by operator name
Based on the government's evaluation, all three Korean operators offer fast 5G, and in cities and on the subway the differences are too small for travelers to notice. The gaps appear when you drop to LTE and when you are on the move, as on the KTX. So when choosing a travel eSIM, first confirm 5G support, then look at the operator names in the supported networks, so you know which network you will fall back to on LTE. After you arrive, check Network Selection on your phone once to see which operator you are on. For Wi-Fi in Korea, see internet and free Wi-Fi in Korea, and for sharing one connection among several people, see pocket Wi-Fi in Korea.
See the plans and supported networks for Korea on the Coral eSIM South Korea plans page, or browse other destinations in the full plan list.
