A friend of mine just bought an iPhone last night. For some reason, some of the texts are coming through green (Sent as Text Message) and others are coming through as blue (iMessages). Usually, the text messages come at the start of a conversation and then convert after a message or 2 into using the iMessage system. Is this a bug? I don't have a text messaging plan anymore specifically due to iMessage and now I'm getting randomly charged for text messages that should be using iMessage.