I bought the Korea SIM card Blue for USD64. Pick-up at the airport as well as activation went smoothly. However, about 4 days into using the SIM card, I started to receive marketing calls, prank calls and even calls from unknown sources telling me that I owed them money. I also received calls in which the caller constantly referred to me as another person. I did not use this number for any purpose except for:
1) Picking up the government's calls (I am under compulsory self quarantine due to the Covid-19 situation) and
2) For a one-off food delivery service (which I had used many times before in Korea and not received any weird messages).
All in all, I feel pretty disappointed after reading all the good reviews about purchasing a SIM card from this website, I did not expect to have to face these issues.