Phone & Internet in Korea
Last updated: October 9, 2026 · Apple, Samsung and travel-eSIM troubleshooting guidance rechecked
Seoul metropolitan subway · Photo: Sgroey / Wikimedia Commons · CC BY-SA 4.0 · Cropped for display
Look at the status bar first. If you see No Service, SOS or Searching, start with the network connection. If you have signal but no internet, check the mobile-data line, roaming requirement and APN.
If mobile data works but calls or SMS don't, check the functions included in the plan you bought.
| What You See | Check First |
|---|---|
| No Service / SOS / Searching | Line enabled → roaming rule → reconnect → network |
| Signal bars, no internet | Data line → roaming → APN |
| Data works, calls/SMS do not | Plan functions |
| SIM/eSIM missing or not detected | Physical SIM / eSIM profile / Dual SIM status |
1. No Service, SOS or Searching
Make sure the Korean SIM or eSIM line is enabled. On a Dual SIM phone, confirm that the travel line hasn't been turned off after installation.
Check the provider's instructions for Data Roaming. Some international travel eSIMs need roaming enabled on the travel line because they connect through a Korean partner network.
Don't switch on roaming for your home SIM unless you're deliberately using your home carrier's roaming service. Depending on your plan, that can result in additional charges.
Then reconnect the radio:
Wait for the phone to search for a network. If service doesn't return, restart the phone once.
If your provider specifies a Korean partner network and automatic selection fails, select the network listed in that provider's instructions.
On iPhone, Apple's troubleshooting guidance also recommends checking for carrier-settings updates while connected to Wi-Fi. Go to Settings → General → About and follow the update prompt if one appears.
If the travel line is active but the phone still can't connect, contact the SIM or eSIM provider. The account may need activation or network provisioning that can't be fixed from the phone alone.
Apple — SOS, No Service or Searching →
2. Signal Bars but No Internet
Signal bars mean the phone has reached a mobile network. They don't necessarily mean that the phone has an active mobile-data connection. Check the data path next.
On a Dual SIM phone, confirm that Mobile Data / Cellular Data is assigned to the Korea SIM or eSIM.
If the provider requires Data Roaming, enable it on the travel line. Don't enable data roaming on the home SIM unless you intend to use your home carrier's roaming service.
Check the provider's APN
APN settings vary by provider. Use the values in the purchase email, installation instructions, provider app or official support page.
On many Galaxy phones, the menu is:
If your provider tells you to add an APN, enter the supplied values exactly and make sure that APN is selected.
On iPhone, manual APN editing may not appear when carrier settings control it. Apple says APN settings can only be viewed or edited when the carrier allows it.
Incorrect APN settings can interrupt mobile data. Follow the provider's exact instructions before changing them.
If the settings look correct but nothing loads, connect to trusted Wi-Fi and ask the provider whether the SIM or eSIM is active and properly provisioned.
Samsung — APN settings →
Apple — View and edit APN settings →
3. Data Works but Calls or SMS Do Not
Open the plan details and check what the product includes.
Korean number — provided?
Incoming calls — supported?
Outgoing calls — supported?
Incoming SMS — supported?
Outgoing SMS — supported?
Many travel eSIMs are data-only, so a working data connection doesn't mean that calls or SMS should also work.
If your plan includes voice or SMS, check which SIM line is selected for calls and messages. On a Dual SIM phone, mobile data and voice calls can be assigned to different lines.
If those functions still fail, contact the provider and ask whether outgoing calls or SMS require activation, a separate balance or a top-up.
A Korean number and formal Korean mobile identity verification are also separate functions. For that distinction, see Do Tourists Need a Korean Phone Number in Korea? →
4. SIM or eSIM Is Missing or Not Detected
Physical SIM
If the phone doesn't detect a physical SIM at all, power the phone off before checking the tray and SIM placement.
Make sure the SIM sits correctly in the tray and that you're using the correct card size. Don't force the tray if it doesn't close normally.
If the SIM is detected but still has no service, return to the network steps in Section 1. If it has signal but no internet, use Section 2.
eSIM
Check that the installed profile still appears in the SIM or Cellular settings and that the line is enabled.
Some travel-eSIM products can't be reinstalled freely after deletion. If the profile is missing, contact the seller and ask whether the original QR code can be used again or whether a replacement must be issued.
Dual SIM
Confirm which line is enabled and which one is assigned to mobile data.
If the provider asks you to isolate the travel line during troubleshooting, temporarily disable the home line and test again.
Remember to restore the home line afterward if you need it for ordinary calls or messages.
5. Still Not Working? Send the Provider Useful Evidence
Connect to trusted Wi-Fi and prepare:
Exact SIM/eSIM product name
Whether the screen shows No Service / SOS / Searching or normal signal bars
A screenshot of the status bar or relevant SIM settings
The troubleshooting steps already completed
This gives the provider useful information to distinguish activation, compatibility, network, APN and provisioning problems.
You can also tell the provider when you installed the SIM or eSIM, when you arrived in Korea and whether the connection has ever worked. Those details can help identify a plan-start or activation problem.
Don't post your full QR code, activation code, account credentials or other sensitive identifiers publicly while seeking support.
If you're still at the installation stage, return to Korea eSIM Setup Guide: How to Install, Activate & Test Your eSIM →
Two Korea Desserts
K-Crafts Making Class — Seoul Hallyu Program
VisitSeoul TV visits Bukchon Traditional Crafts Center, where participants try Korean traditional crafts in a hanok setting.
Open on YouTube →Factual checks: Apple Support, Samsung Support and provider-specific travel-SIM guidance. Menu names, APN values, roaming requirements and partner networks vary by device and product. Follow the instructions supplied with your purchased plan.