How to de-register your phone number from iMessage and FaceTime (detailed iOS 8 tutorial)15
The problems that marred iMessage a few months ago, in November 2014, immediately pop in mind: users who had switched to another platform could not receive the SMS messages they were being sent as they passed through the iMessage service and did not reach their intended destination. This was one of the main reasons why Apple released a handy new feature that allows you to de-register your phone number from the iMessage service and resolve any issues you might have with your transition from one platform to another.
Here's how to do it if you still have your iPhone/iPad around.
But what can one do if they no longer have their iDevice at hand? Fortunately, Apple has an online tool that allows you to easily de-register your phone number from the iMessage service. Here's how.