Prepaid Korean SIM Cards are available for only foreigners (Foreign Passport Holders). You will need (1) Unlocked Smartphone, (2) Passport, and (3) Credit Card or Cash to pay for a SIM Card. I handed all three to a store person. She CINFIDENTLY setup the SIM Card configuration and took a picture of my passport in order to activate the SIM Card. When she gave my phone back along with a brochure, everything was all ready to use.
There were three different plan types at this time. I paid about US$29 (31,000 Korean Won) for ‘Basic A Plan’. The other two plans are: 1GB Combo Plan–about US$32 (35,000 Korean Won) and 2GB Combo Plan–about US$45 (49,000 Korean Won). Based on my previous experiences, it seems the usage is calculated between calls, messages, and data but I didn’t bother to figure it out. It also appeared that the price includes the physical SIM Card because the beginning balance was less than what I actually paid. It says that this prepaid SIM card is valid for 30 days. However, on my prior trip, I was able to extend the duration and recharge more money by calling customer service.