Instructions on how to charge your credit can be found in the manual that comes with the SIM card. You can extend the validity of the SIM card for 1/5/10/30 days. *Credit charging is required before usage. You will receive a handout on how to charge and extend your SIM card when you pick up your SIM card.
*After you use all of the 3GB of data per day, you will be able to use unlimited data at 5mbps speeds.
(Voice/SMS is available after charging credits.) Stay connected 24/7 everywhere in Korea with this data only SIM card with unlimited LTE data usage on Korea's largest wireless operator! Get unlimited data and if you would like to make calls or send texts simply charge credits! Just make sure your phone is unlocked to be able to use this SIM. If you are a solo traveler, I would recommend getting a SIM card over a Wifi Egg as you only need to worry about charging your phone and don't have to carry an extra device around. Connection was stable wherever I went in Seoul, I was provided with a local phone number, and although the speed isn't the fastest, it seems to be unlimited. Overall, I had a great experience using this SIM card for 10 days. The only flaw would be the speed, which was not as fast as expected for LTE (See attached photo), however, it does seem to be unlimited as I used it all day streaming videos and music with no issues. The SIM was essential for me during my trip as it allowed me to connect to google maps, research on different locations, check email, etc. It even worked during my 2 day trip to Vivaldi Park - Daemyung Resort, which was almost 2 hours away from Seoul. The SIM Card worked all over Seoul with no issues in connection. Both proved to be useful in communicating with the hotel & airbnb that I booked. SIM included both data and a phone number. The directions were helpful and the process to get the SIM was smooth. Picked up SIM card at the KT Roaming Booth in Incheon.