Folks who’ve moved away from the iPhone will be far too familiar with this problem.
Apple’s iMessage system will automatically detect if an iPhone user is sending a message to another iPhone user based on phone number. If the destination phone number is registered with iMessage, then it will automatically use iMessage. But what happens when the destination phone number is no longer on an iPhone? Well the message is lost forever…
For the people moving away from iPhone, Apple has provided an easy way to deregister your number from iMessage so that iPhone users are no longer trying to send you iMessage’s.
If you still have your old iPhone… you can deregister it by following the provided steps.
If you’ve already sold your iPhone, then all you’ll have to do is head to https://selfsolve.apple.com/deregister-imessage and enter your phone number. Apple will then send you a txt message with a 6 digit confirmation number. Enter that confirmation number and iPhone users will no longer see you as an iMessage device. [APPLE]