Four minutes at home · nothing at Incheon

Setting up your Korea eSIM

Do this on your own wifi the night before. Every eSIM problem that spoils a first morning in Seoul was fixable at home with a working connection and no jet lag.

A phone showing cellular settings on a Seoul hotel desk beside a passport and boarding pass, with Han river bridge lights through the window — Yeouido, 23:10, the Korea line labelled and switched off until landing

Quick answerDial *#06#. If an EID appears, your phone takes an eSIM. Buy the plan at home, install it on your own wifi, label the line "Korea", and leave it off until you land. At Incheon: Korea line on for data, home line on for calls with data roaming off. If nothing attaches after five minutes, switch network selection to manual and pick SKT if you bought Airalo. Flying on to Jeju: install before you go, there are no carrier counters at Jeju airport. Checked September 7, 2026.

Three things to check before you buy a Korea eSIM two minutes

Does the phone take an eSIM? Dial *#06#. An EID in the list means yes. No EID means no eSIM, and the route is a physical SIM instead. Most iPhones from the XS on and most flagship Android handsets from about 2020 qualify.
Is the phone carrier-locked? A locked handset installs the profile and then refuses to use it. US carriers unlock for free once the device is paid off; allow a day or two.
Do you need a Korean phone number? This is the Korea-specific question. Every plan we link is data only, and in 2026 that is enough for Naver, Kakao T, Baemin and CatchTable. Coupang still wants a Korean-carrier SMS. If you need a 010 number, read this before buying anything, because the answer is a carrier eSIM and a passport, not a travel eSIM.

Installing the Korea eSIM profile at home, on wifi

iPhone

Buy the plan and open the confirmation on the phone, or hold the QR code on another screen.
Settings, Cellular, Add eSIM. Airalo, Saily and GigSky all offer one-tap install from their apps, which beats the QR route.
Label the line Korea. Not "Travel". You may be toggling it in the immigration queue at Incheon.
Turn the new line off for now. Validity starts on first connection to a Korean network, not on install.
Check Settings, Cellular, Cellular Data still points at your home line. Nothing changes until you land.

Android

Buy the plan and open the confirmation, or have the QR code ready elsewhere.
Settings, Network and internet, SIMs, Add eSIM. Samsung: Connections, SIM manager, Add eSIM. Pixel: the plus button beside SIMs.
Name it Korea.
Leave it disabled until the wheels are down.
Confirm the home SIM is still default for data, calls and SMS.

Do not plan to scan the QR at Incheon, and do not plan to buy anything at Jeju. Installing a profile needs a working connection, which is the one thing arrivals does not give you. And Jeju airport has had no carrier counters since the end of June 2026: SKT closed its roaming center there and KT left in 2018. Guides that say "pick up a SIM when you land on Jeju" are describing a counter that no longer exists. Install before the domestic flight. More on the counters.

What to do when the plane lands at Incheon thirty seconds

Airplane mode off, then wait. Give the phone two or three minutes; it is scanning three Korean networks it has never met.
Enable the Korea line. iPhone: Settings, Cellular, tap Korea, turn it on, set Cellular Data to it. Android: Settings, SIMs, enable Korea, set as mobile data.
Home line on for calls and SMS, data roaming OFF. This is the toggle that stops the $10-to-$12-a-day charge while your own number keeps receiving bank codes.
Glance at the carrier name. The status bar will read SKT, KT or LG U+, in Latin letters on every handset we know of. If you bought Airalo and see SKT, everything is as published. On Saily, GigSky and Yesim the network is not published, so whatever appears is simply what you got. What each name means.

Korea eSIM not working: symptom to fix in the order to try them

Symptom	Most likely cause	Fix
No service at all, five minutes after landing	The scan has not finished, or the line is off	Airplane mode on and off. Then confirm the Korea line is enabled and set as the data line.
Connected, no internet	Cellular data still points at your home line	iPhone: Settings, Cellular, Cellular Data, choose Korea. Android: SIMs, mobile data, choose Korea.
Still nothing after ten minutes	The phone attached to a network your plan cannot use	Turn off automatic network selection and pick by hand. SKT for Airalo, which publishes SK Telecom. For Saily, GigSky and Yesim the network is not published, so try each of SKT, KT and LG U+ in turn and stay on the one that connects.
Signal vanishes on the KTX, comes back a minute later	A tunnel	Nothing. The line south of Daejeon runs through long tunnels and all three carriers drop in the same ones; the regulator's 2025 measurements put rail 5G at 393 Mbps against 974 nationwide. The KTX section here.
"No service" deep in a valley, on a plan riding LG U+	LG U+ has no 3G layer to fall back on	Nothing to fix on the spot. LG U+ never built 3G, so where its LTE ends the phone goes straight to no service instead of stepping down. Ubigi and Holafly list LG U+ as a network; move a few hundred meters or wait. Not a fault in the eSIM.
Near the DMZ the phone offers an unfamiliar network	You are picking up a North Korean carrier across the line	Do not connect to it. Leave selection on automatic and, if it has latched on, choose SKT, KT or LG U+ manually. At Imjingak and the Third Tunnel the Korean networks are fine.
Very slow, but connected	You crossed a daily cap on an unlimited plan	Wait for the daily reset. Airalo slows to 1 Mbps after 3GB, Saily after 5GB. All the caps.
Data running out faster than the plan said	Naver Map re-downloading tiles, or photo backup over cellular	Save offline areas in Naver Map for each city, and turn off cellular backup in Photos. A Jeju driving day with live tiles is the classic. More ways to use less.
T-money card or the subway gate not working	Nothing to do with your eSIM	T-money is a stored-value card with no data, no app and no phone number involved. Top up with cash at any convenience store or at the Line 1 to 8 machines, which have taken overseas cards since March 2026.
A Korean app rejects your number	It wants a Korean-carrier SMS	Data-only eSIMs do not include a number. Coupang is the main app that still insists on one in 2026; Naver, Baemin, Kakao T and CatchTable no longer do. The 010-number page.
Profile will not install	Carrier lock, or no wifi	Install on wifi only. If it fails on home wifi, the handset is probably locked and the provider's support is next.

Find the manual network menu before you fly. iPhone: Settings, Cellular, tap the line, Network Selection, Automatic off. Android: Settings, Network and internet, SIMs, tap the eSIM, turn off automatic selection. Learning where it lives on a Seoraksan trail with one bar and a bus at 16:40 is not the plan.

The night-before checklist for a Korea eSIM eight lines

Dialled *#06# and saw an EID.
Phone unlocked, confirmed with the carrier rather than assumed.
Plan bought and profile installed, on home wifi, labelled Korea, switched off.
Offline areas saved in Naver Map for Seoul, Busan, Jeju and anywhere else on the route.
KakaoTalk installed and verified on your home number while it still has signal. A US number works for signup; only Kakao Pay wants a 010.
Papago installed with the Korean offline pack downloaded.
Cellular photo backup switched off.
GigSky's free 100MB installed as a spare. No card, seven days, expires on its own, and it tells you which Korean network your handset attaches to before you spend anything. GigSky pays us the highest commission of any brand here; the free trial pays us nothing.

Korea eSIM setup questions short answers

When should I install my Korea eSIM?

At home, on your own wifi, the day before you fly. Validity starts when the profile first connects to a Korean network, so installing early costs nothing, and trying it in the arrivals hall at Incheon means downloading a profile with no connection to download it over. If Jeju is on the itinerary, this matters twice: the airport there has had no carrier counters since June 2026.

Which network should I select manually in Korea?

SKT if you bought Airalo, which publishes SK Telecom as its Korean network. Saily, GigSky and Yesim do not publish theirs, so try SKT, KT and LG U+ in turn and stay on whichever connects. Ubigi and Holafly list SK Telecom and LG U+. Near the DMZ, never select a network you do not recognise; it may be North Korean.

Can I keep my US number while using a Korea eSIM?

Yes, and it is the main reason to prefer an eSIM over a physical Korean SIM. Leave the home line on for calls and texts with data roaming off, and set the Korea line as the data line. Bank codes and two-factor texts still arrive on your own number without a roaming day pass.

Why does my eSIM lose signal on the KTX?

Tunnels, and it is the same on every carrier. Korea's regulator measured high-speed rail 5G at 393 Mbps against 974 Mbps nationwide in 2025, with 19 of 32 weak-5G zones on rail sections. If the signal returns as the train leaves the tunnel, nothing is wrong with the eSIM. Download the episode on hotel wifi.

Do I need a Korean phone number for Korean apps?

Less than any 2025 guide says. Naver's passport verification, launched June 2026, unlocks Naver Booking and Pay without a Korean number; Baemin has taken orders without one since summer 2026; Kakao T accepts +1 numbers; CatchTable works on email. Coupang still needs a Korean-carrier SMS. A data-only eSIM covers everything else.

Install the free one tonight

GigSky gives away 100MB for seven days with no card. Install it now, land at Incheon with a working phone whatever else happens, and see which Korean network your handset picks before you pay for anything. GigSky pays us the highest commission on this site when you do buy; the trial itself earns us nothing.

Get GigSky free 100MB

Sources & freshness: Menu paths checked against current iOS and Android releases and vary slightly by manufacturer, particularly Samsung. Network claims are each brand's published statements on September 7, 2026, not our tests. The Jeju counter closure is from a May 2026 Korean news report of SKT's exit at the end of June 2026; rail figures from the Ministry of Science and ICT 2025 quality evaluation; LG U+'s lack of a 3G layer and the DMZ network behaviour are from traveler reports and carrier history, not our measurements. T-money card acceptance from Visit Seoul, March 2026. How we test.