Hey,
I'm not sure how many people will still be reading this but I thought that I'd put all the information I've gathered into one place for everyone else to find.
First things first. I had an iPhone, it was good at what it did, but I didn't like how limited it was so when I got a new phone I moved to an Android device. It was a quiet couple of days...
I learned that Apple, with it's imessage function, actually highjacks your texts to other Apple device users and sends them through your 3G/wifi connection and their servers to the other users. They completely bypass the typical SMS route which could be nice if you were still paying for your texts individually, but who really is nowadays? Anyways, once you've sent any apple user a message like this you're in the system and you've gotta get out before it's going to work for you on another device.
To be able to receive texts/picture messages/etc. on your non-Apple device you'll need to go to
https://supportprofile.apple.com/MySupportProfile.do sign in, find your old device(s) and Unregister them by clicking on the "x" beside them and then the "Unregister" button.
Make sure you do this for each device linked to that phone number!
After you've done this you'll have to wait. Some people have said that it was only a few minutes, it took closer to two days for my account to be fixed.
Another workaround that I've heard works is to have each of your friends go into your contact info and either delete it and start again, or change your contact number from an iPhone to "Mobile" then restart their devices... and wait till it takes effect.
I understand that this is a VERY frustrating problem and I hope this helps!
-J
PS - Please don't hate on your new phones because they aren't working. Hate on Apple for knowing about this problem for a year and not fixing it yet because it sometimes gets people to give up their other devices and come back to them... Shady.
EDIT:
PPS - If you got a new number and are having the problem it's probably because the person that had the number before you had an Apple. If that's the case you're outta luck. You're not going to be able to get Apple to modify that random strangers' account, and there's nothing your service provider can do because your phone is working the way it "should" be. Just ask for a new # and if you can, specify one that hasn't been used before so you know that it's clean and fresh!