iPhone 4, 5.0.1. Recently, i've turned off iMessage since i've started using Whatsapp extensively, plus my carrier plan has 3000sms'n'mms/month so no need for cheapo iMessage stuff... But the day i've turned iMessage off strange things started to happen: all the ppl that were chatting with me via iMessage STILL sent me lots of messages via iMessage (the SEND buttin was STILL blue on their iPhones!) and so i didn't receive all these messages! What's worse, EVEN if they delete the conversation and start the new one, the Send button is STILL blue! I've tried erase all content and settings as new and erase all content and settings with iCloud backup but NOTHING helps! I just can't get make THEIR iPhones KNOW that i am NOT using iMessage ANYMORE! Any help?????