Overview

– After inserting your new Korea SIM card, it will usually connect automatically and start working right away.
– However, in some cases, the SIM card may not work immediately. If you experience any issues, please check the following common situations and solutions.

1. Your Phone Is Not Connecting to the service provider’s Network in Korea

(1) When Your Phone Shows “No Service”:

– This is one of the most common situations. Sometimes your phone may not recognize the SIM card immediately and therefore cannot connect to the network.
– Try the following steps:
– Turn your phone off and on two or three times.
– Check whether the LTE signal appears.
– In some cases, you may need to repeat this process several times.
– If your phone continues to display “No Service,” your IMEI may need to be registered in the KT network system.

(2) Calls and Texts Work, but LTE Data Does Not
– In most cases, the APN (Access Point Name) settings are configured automatically when you insert a new SIM card.
– If the APN is not configured automatically, voice calls and text messages may work, but mobile data will not.
– In this case, you can manually configure the APN settings and start using LTE data immediately.
– SKT or KT or LGU+ APN Settings for iPhone and Android

(3) LTE Data Works, but Calls and Texts Do Not
– To use voice calls and SMS services in Korea, your phone must support 3G (WCDMA) networks.
– If your phone does not support 3G, LTE data may work normally, but voice calls and text messages will not be available.
– Please check your phone’s network compatibility before traveling to Korea.

2. Your Phone Is Carrier Locked

– Make sure your phone is fully unlocked before using a Korea SIM card.
– If you insert a Korea SIM card into a carrier-locked phone (or Installed Korea eSIM), you may see one of the following messages.

* iPhone
– SIM Not Supported
– SIM Not Valid

* Android
– Operator Change
– Enter SIM Network Unlock PIN
– The SIM Card Is Incorrect

– At first glance, it may appear that there is a problem with the SIM card.
– However, these messages usually indicate that your phone is carrier locked and cannot accept SIM cards from other mobile operators.
– Please contact your carrier and confirm that your phone is fully unlocked before traveling to Korea.

* Additional notes:
– In some cases, the unlocking process may take time.
– Search for “unlock request” together with your carrier’s name for detailed instructions.
– If you are using AT&T or T Mobile, you may be able to submit an online unlock request and receive approval on the same day.

* Tip: How to Check If Your Phone Is Unlocked
– Insert a SIM card from another carrier.
– If the phone works normally, your phone is unlocked.

3. Your Phone Shows “No SIM”

– Although this issue is uncommon today, it can occasionally occur.
Instead of showing an LTE signal, your phone may display “No SIM.”
If the same problem occurs when the SIM card is inserted into another phone, the SIM card may be This guide will help you identify whether your phone is locked, your settings are incorrect, or your Korea SIM card is defective..
Please contact us immediately and we will arrange a replacement SIM card for you.

After switching New SIM Card, most Korea SIM Cards are automatically connected and work immediately.
However, sometimes you might feel embarrassed because it doesn’t work automatically.
Please check if you meet the trouble one of following cases or not.