If you have international roaming on your phone enabled (most people do) you should be able to send SMS text messages to people abroad, right? Not if you’re with O2 it turns out. Having switched to O2 at the beginning of the month, because they’ll be the sole iPhone carrier in the UK, I found out to my great annoyance this week that you can’t SMS people in South Korea and visa versa… if you’re on O2 anyway (Orange works fine). Several missed text messages later, which mysteriously vanished into a black hole somewhere, I called and emailed customer services who eventually came back with this: “Thanks for emailing us about not being able to send text messages to a South Korean mobile number.…