I have 3 iPhones on my family plan. We text each other most of the day. Every month my bills show texts from one line to the other? It lists "some" of them and not "all of them". What would make a text green instead of blue when it's going to another ios5 device? I recently took off unlimited messaging and now I'm terrified than these will be billed 20 cents per text but realistically they shouldn't be billed anything. Help!