I've also noticed that once you have an iphone if another iphone user adds you as a contact it stores your number as "iPhone" in the contact card type. When I'

I've also noticed that once you have an iphone if another iphone user adds you as a contact it stores your number as "iPhone" in the contact card type. When I've switched back and forth from Android on a few occasions I've had to have users update that contact card for SMS to work properly. I don't think its necessarily an iMessage issue more iOS, but if anyone is still having issues with the switch after de-registering, check that.