eSIM not working in South Korea
Your Drift Asia eSIM has no data in South Korea? Here is the real fix, step by step, iPhone and Android, with South Korea operator APN reference.
Networks in South Korea
South Korea has 3 major operators, all compatible with travel eSIMs:
| Operator | Coverage | Technology |
|---|---|---|
| SK Telecom | 1er réseau, meilleure couverture 5G | 4G/5G |
| KT | 2e réseau (ex-Korea Telecom) | 4G/5G |
| LG U+ | 3e réseau, fort en 5G | 4G/5G |
Your eSIM connects to one of these networks (most often SK Telecom). 4G coverage spans the large majority of tourist and urban areas.
Diagnosis in 5 steps (in this order)
Work through these before anything else. Nine times out of ten, the fix is in this list.
Steps 2 and 3 fix the large majority of cases. Data roaming is required for any travel eSIM. It does not add charges on a Drift Asia plan.
Airplane mode as a diagnostic tool
Toggling airplane mode forces the phone to detach from the network and search fresh. It is faster than a full restart and clears most handover issues (when the phone stays attached to a ghost signal after a long flight). If after the toggle you see the operator name on screen but still have no data, the issue is almost certainly roaming (step 2) or data line (step 3).
Signal bars vs. data
A common trap: you see signal bars but nothing loads. Bars mean the phone detects the network, not that it is authorized to exchange data. That is exactly what happens with roaming off: signal is there, but the network refuses your data packets. Turn roaming on and data resumes.
APN in South Korea: do you need to set it?
No, in 99% of cases. Your travel eSIM sets its own APN automatically via the installed profile.
Do not enter your home operator's APN or a SK Telecom APN found online into the eSIM line. Those are APNs for local physical SIMs, not travel eSIMs. Entering one overwrites the profile's APN and breaks your data instead of fixing it.
For reference only (do NOT enter these on your eSIM line):
| Operator | Primary APN | Alt APN | Note |
|---|---|---|---|
| SK Telecom | lte.sktelecom.com | -- | 1er réseau, meilleure couverture 5G |
| KT | lte.ktfwing.com | -- | 2e réseau (ex-Korea Telecom) |
| LG U+ | internet.lguplus.co.kr | -- | 3e réseau, fort en 5G |
Manual APN entry only if support asks with a specific value. Full procedure: Do I need to set an APN?
Country-specific notes for South Korea
Seoul metro and KTX
The Seoul metro has full 4G coverage, including tunnels. The KTX (high-speed train, Seoul to Busan) also has excellent coverage with only brief drops in tunnels. South Korea has one of the densest mobile networks in the world.
Jeju Island
Jeju has excellent 4G/5G coverage across the island, including hiking trails on Hallasan. No issues expected.
Rural areas
Even rural South Korea is extremely well covered. You are unlikely to find a dead zone in any area a tourist would visit.
Still not working?
Prepare these three things and contact support:
Support typically identifies the cause in a single exchange.
FAQ
Why does my eSIM have no signal in South Korea?
Most likely data roaming is not turned on for the eSIM line. Enable it in your mobile data settings. If you see signal bars but no data, also check that the eSIM is set as your data line.
What APN should I use for my eSIM in South Korea?
None. The eSIM sets its own APN automatically. Do not enter an APN for SK Telecom or any other local operator.
Do I need to enable roaming to use my eSIM in South Korea?
Yes, it is required. Data roaming must be ON for the eSIM line. There is no extra charge. Roaming is already included in your plan.
My eSIM worked yesterday in South Korea but not today. What do I do?
Check that your plan is not expired or used up. If it is still valid, toggle airplane mode (10 seconds on, then off). If that does not help, force network selection to SK Telecom then switch back to automatic.
Do I need to worry about coverage anywhere in South Korea?
Almost nowhere. South Korea has one of the densest mobile networks in the world. Even Jeju Island and rural areas have excellent 4G/5G coverage.