Iphone users cannot text me after switching platforms. Please Help

Question

Ok, So I just started a new job and have been assigned a company phone. My company phone is a Samsung Note 3. I have been using an AT&T iPhone 5. I went a day or so with very little text messages coming on to the phone and was currious why i was not getting responses from friends. After an angry phone call from my boss, I realized I was only getting text messages from Andriod Users. So I gathered my roommates and had them text me to figure why I was not getting texts. The iPhone users could not text me but i could text them. The android users had no issue. I looked at their phones and it was sending the message to me as an iMessage which i wont be able to recieve. I googled the issue and found other users with the same thing. I traded in my phone today so i dont have access to the iPhone any longer.
This is what ive tried:
Logged into iMessage on my Mac:
Went to Preferences --> Accounts --> Unclicked my phone number (and eventually just shut it off all together)
After this: No Change
Logged into iTunes on my Mac:
Went to Itunes Store --> Account --> Itunes in the Cloud --> Unauthorized my iPhone from this section
After this No Change
When to the Apple Support Community
Went to: https://supportprofile.apple.com/MySupportProfile.do
Clicked on “edit products”
Clicked on the “x” to the right of the product.
Clicked “unregister”
After this: No Change
Went to iforgot.apple.com
I Changed my password, in hopes that it would disconnect my phone
After this: No Change
Grabbed my friends iPhone 5,
Disconnected his apple id and logged into mine
I toggled the iMessage slider to see if it would disconnect.
Logged off the iCloud Account on that device leaving iMessage off
After this: No Change
Called At&T Customer Support (By Far the Most Frustrating)
The guy proceeded to tell me that I should contact all of my iPhone using friends and tell them that every time they text me they need to long press the text bubble and select "Send as Text Message". After 45 mins, I just gave up. The conversation ended with the rep telling me that i should just swich back to iPhone. I talked to his manager and got a months statement credit for that one, so it wasnt a complete loss.
I own 3 macbook pros, a mac mini, a mac pro, 2 ipads, and a ipad mini. Im very frustrated and if I cannot get this resolved, I will seriously reconsider any apple purchase i make in the future.
Please Help!

Answer 1

http://support.apple.com/kb/TS2755 noted:
If you plan on transferring your SIM card or phone number from an iPhone to a device that does not support iMessage, turn off iMessage in Settings > Messages first. If you do not, other iOS devices may continue to try to send a message using iMessage first, instead only using SMS or MMS.
If you have not turned off iMessage for your phone number before you use it on a non-iOS device, it will be detected by other iOS device as still on iMessage.  What you can do is put back your number/SIM on an iPhone then activate then deactivate iMessage once successfully activated to de-register that phone number from iMessage server.  Hope it helps.