I had to wait like 30 minutes before the staffs could resolve the situation. I don't have foreigner number for god sake!! Google and NESPOT has collaborated for free Wi-Fi internet access in Starbucks all over Korea. The only PROBLEM is that you need to key in your foreigner no in foreign card which for some tourist they don't have it. So if you ever seen this page when you first accessing the free internet access:
What you must do:
1. Please install hangul/korean IME - Try Declan's method or go to Microsoft website to install the Korean IME. --Why you need to do this? Cause your LapT most probably are not with Korean keyboard ^_^
2. Ask the Starbucks staff to access from their KOREAN website, using their own ID - which they will need hangul to solve this.
3. Yeayy!! You can access now. ^_^
Note: I went to another Starbucks and the staff refused to lend me his ID. If that happens, just hop to another coffee shop like Holly's or Cafe' Bene where they don't require you to key in Korean ID/Alien Registration No.