Can You Use Your iPhone 4 or 4s in Korea???

Before arriving in Korea, I tried researching online to see if I could possibly use my iPhone 4s in Korea. I figured it had to be factory unlocked and that would be the only pre-requisite to getting my phone set up. Unfortunately, I couldn't find any YouTube videos on that particular topic. I asked around as much as I could to my fellow EPIK teachers and just like me, we were all lost and had no idea where to find that information. The main thing that kept circling around us was that it would be not only difficult to find a sim card that "fit" an iPhone 4 but that if you got lucky, your contract would be sky high. Heard numerous stories of how Koreans don't like Apple products and that your iPhone will most likely not be compatible. I decided to pre-purchase a Korean phone because I didn't want to take chances of being stranded at the airport and with no communication since I was traveling solo. F.Y.I. there are many pay phones posted at the Incheon Airport. Once arriving in Korea, it was fairly simple getting around the airport and the customer service was amazing. I never once got lost because every staff member that helped gave me clear and concise directions. I bought a bus ticket to Osan Air Base to visit a friend for the weekend and as soon as I met with her, I noticed she had an iPhone in her hand and so did her friend! I soon came to find out through them that getting your iphone set up in Korea is not at all like I had imagined it would be. I literally went down the street and found a pre-paid store that sold sim cards and phones. The sales guy popped in a korean sim card and activated it in under 20 minutes. It cost me $30 ($10 for sim, $10 for minutes and data, and $10 for activation fee). The monthly pre-paid plan is about $10 a month with 60 minutes and 1 GB of data. That may not seem much to you but for me it was perfect being able to get this service immediately. I have apps like whats app, viber, and magic jack that allows me to communicate for free and get by in the time being until I find other options and possibly even a contract later on down the line, should I decide to go down that route. For now this will do and I truly regret going with a Korean phone initially, not because there is anything wrong with one but because I wasted money doing so. I'm hoping that this video can benefit someone else and yield them from making the same mistake as I did.