v.12 updated at 2022. 08. 16
The new Q-Code system ( https://cov19ent.kdca.go.kr/cpassportal/biz/beffatstmnt/main.do?lang=en ), the Quarantine Information Advance Input System by Korean Government, has been applied. Please following instructions.
1. For unlocked eSIM-supported smartphone (Unlimited Data + Phone number for receiving voice and messages)
1) Buy Korea eSIM Red ( https://www.krsim.net/product/Korea-eSIM-Red-4G-LTE-Unlimited-Data/71 ) for Android or iPhone, or
Buy Korea eSIM SKY. ( https://www.krsim.net/product/korea-esim-sky-4G-LTE-Unlimited-data/60/ ) for iPhone only.
2) Receive a voucher email with a QR code and a Korean phone number (in a few minutes).
3) Contact to Q-Code system ( https://cov19ent.kdca.go.kr/cpassportal/ ) and input your information with the above phone number.
4) Boarding a plane and landing at Incheon International Airport.
5) Connecting Airport Wi-Fi (SSID: Airport Wi-Fi) and scan the eSIM QR code you received in the setting menu.
6) In case of Sky, Activate Online eSIM activation application ( https://www.krsim.net/esimact )
7) Pass the immigration and Enter South Korea.

2. If you want full mobile services(Phone number + Unlimited Voice, Message and Data)
1) Purchase Korea SIM Blue Plus ( https://www.krsim.net/product/Korea-SIM-Blue-Plus-4G-LTE-Unlimited-Data-Local-Voice-USIM/40/ ). And input the hotel address for the SIM delivery.
2) Receive confirmation email (in a few minutes)
3) Ask the phone number for you through the messenger on krsim.net with your order number on one day before the date you designate as a delivery pick up. (If it is weekend or holiday, on the prior working day)
4) Contact to Q-Code system ( https://cov19ent.kdca.go.kr/cpassportal/ ) and input your information.
5) Boarding a plane and landing at Incheon International Airport.
6) Pass the immigration and Enter South Korea.
7) Collect the Korea SIM Blue Plus you have delivered and check the phone number.
3. Phones without eSIM function. (Unlimited Data + Phone number for receiving voice and messages)
1) Purchase Korea SIM Gold. ( https://www.krsim.net/product/Korea-SIM-Gold-4G-LTE-Unlimited-Data-Only-USIM/44/ )
2) Receive voucher email including order number (in a few minutes)
3) Contact to Q-Code system ( https://cov19ent.kdca.go.kr/cpassportal/ ) and input your information. Check ‘I do not possess a mobile phone’ and input the phone number of the hotel as a available contact phone number in Korea.
4) Boarding a plane and landing at Incheon International Airport.
5) Pass the immigration and collect baggage.
6) Visit SK Telecom Desk and pick-up USIM (check the phone number).
a. Incheon Airport Terminal 1 : between Gate #9~#10; 24 hours / 7 days
b. Incheon Airport Terminal 2 : between Gate #4~#5; 24 hours / 7 days
7) Update to the phone number for Korea SIM Gold on the Q-Code system.

Detail
Starting April 1, Officials announced that travelers who have completed vaccination overseas and registered their vaccination history with Quarantine COVID19 Defense (Q-Code) system will be able to enter South Korea without a seven-day quarantine period. However, this does not apply to vaccinated visitors from Pakistan, Uzbekistan, Ukraine, and Myanmar, and must quarantine for seven days.
If you are considered as a fully vaccinated traveler, you must have received two doses of a WHO-approved vaccine (1st for Jansen) 14 days before arrival (valid up to 180 days) or received a third( booster) shot (there is no limit to number of days post booster shot).
Some restrictions haven’t changed for arrivals. PCR tests are still required for people entering Korea. They must provide proof of a negative COVID-19 PCR test taken within 48 hours of their departure. Another PCR test must be taken the day after arrival at a public health center. The third test on the seventh day is still required, but it can be an antigen test starting next month.
Q-CODE (Quarantine COVID19 Defense System)
International visitors must register their vaccine status on the Q-CODE website before arriving in Korea. The QR code will be provided which you must scan at immigration. When registering, Q-CODE will ask for your personal information (including passport number), entry information (departure country, airline, address in Korea, phone number) and vaccine records. Anyone who inputs normal quarantine information through Q-code will be able to be fast and convenient quarantine inspection.
Furthermore, you can only input all the information on the Q-Code website within 2 days from your departure date because one of the information you must input is the PCR negative test result which must take place within 48 hours from departure date.
If you input false or inaccurate information related to the Q-code, you may incur a penalty or be subjected to entry restriction in accordance with the relevant laws and ordinances of the Republic of Korea. The same law applies when you submit false or inaccurate QR-code by proxy.
1. If your device is an eSIM-supported smartphone,
Some of the recently released smartphones have an eSIM function. Even if you don’t have to use a physical SIM card, you can enjoy the same effect as inserting a physical SIM card into your iPhone through download. It is the most convenient and recommended way. You can check whether your smartphone supports eSIM in Setting. If your phone is not bound(locked) to a mobile carrier and appear as shown on the screen above in the setting, I strongly recommend using eSIM.
Korea eSIM Red and Sky are the only two eSIM products that currently provides Korean phone numbers, so there is no other choice. It provides unlimited data. With eSIM Red, you can enjoy unlimited data with no speed down in Korea. For Sky, To be precise, 3GB full speed is provided unlimitedly per day, and after using 3GB, unlimited data is provided at 5Mbps. And a new 3GB will be provided again at midnight every day. The 5Mbps speed is even possible for YouTube streaming.
eSIM Red is from SK Telecom and eSIM Sky from LG Uplus, You can purchase them cheaper if you purchase it on the Korea SIM card website than directly from SK Telecom or LG Uplus.
You can receive an e-mail with a QR code and a Korean phone number (in a few minutes) after ordering. The email voucher already contained a Korean phone number, so you can input the quarantine information in Q-code from the time of purchasing a flight ticket and preparing for travel, before boarding a flight to Korea.
As soon as getting off the plane at Incheon International Airport, you can apply for online activation(in case of eSIM Sky) and scan the QR code with airport Wi-Fi. The next steps are the same as normal immigration procedures.
2. if your phone doesn’t support eSIM ,
In this case, Korea SIM Gold is a best choice. It is a product provided by SK Telecom, Korea’s No. 1 mobile carrier, and SK Telecom is collaborating with Incheon International Airport.
Korea SIM Gold is basically a USIM that provides unlimited data without speed limits, but it also provides additional functions such as incoming voice calls and text messages with Korean phone numbers (Starting 010- ) when ordering online and picking up at the airport. Since outgoing voice calls and text messages are impossible, voice calls can be made using data such as FaceTime and Messenger app. You don’t need an activation process, and you can use it after rebooting 2-3 times your phone.
Like eSIM, it is recommended to purchase on the Korea SIM card website at a lower price than on the SK Telecom website. (Photo)
When ordering online, the order number is listed in the e-mail you receive, and you can pick-up USIM by showing this order number to SK Telecom Desk. The USIM contains a Korean phone number starting with 010. Depending on the terminal you arrive at (Terminal 1 or Terminal 2), the pick-up location and operating time can be different.
SK Telecom desk is located in the arrival hall after quarantine, immigration, and baggage claim. Therefore, you need to input your information in Q-Code system before receiving SIM card. If you check ‘I do not possess a mobile phone’ on the stay information page, you can enter the phone number of the hotel as an available contact phone number in Korea. In other words, you can input the temporary available phone number first, and then you can update the number after picking SIM card up. After passing the quarantine inspection and entering the country with the QR code through Q-Code system, you can visit the SK Telecom desk and pick it up the SIM card. When you receive it, you can notify the changed information to the quarantine officer in Korea.