Hello, I have got one Korean version of Galaxy S4 (SHV E300L), with U+. I am using it on a different country.
Everything works fine, except the video call; and I can't find any option to turn on call waiting or call barring (option is not available inside Settings > Call Settings > Additional Settings).
When I try to make a video call, it returns this message: "video call not supported in international roaming area".
Any idea how can I fix these issues? I am running on Android 4.3
Also there is a mark on the top area of the phone's desktop, which I don't understand. Please check the image (marked in red color):