My iphone keeps sending imessages as a texts?

My iphone keeps sending imessages as a texts even thought I unchecked the box in settings saying "if imessage fails, send as a text"… What should I do? When I start typing it shows blue bubble but while trying to send the message it turns green and sends it as a text and this is getting quite expensive from Slovakia to Canada. Any ideas?

That means imessage is down because Apple is fixing bugs in software happens all the time