I’d posted before that it’s a little bit difficult to get a cellphone in Korea if you don’t have a Korean ID. However, if you find yourself in Seoul one day and you’d like to get a phone you might want to visit ACE Telecom (pictured above). I just saw this place when I took my son to a park near Dongguk University. The shop is located at Dongdae or Dongguk University station on Line 3, near exit 6.
My mistake is that I didn’t bother to ask how a foreigner could get a phone. Their sign seems to assure that “Foreigners OK!” I’d try to ask them for details when I visit the place again.