Whenever you start using the iMessage service your phone number is validated for this system and iOS keeps track of this setting. If you don’t turn the service off, before switching from iPhone to another smartphone, the iMessage platform won’t know that you’re not on iOS anymore and will continue encourage your contacts to send iMessages to you. Obviously, you’ll never be able to receive them. More, the sender won’t be able to receive any kind of confirmation and thus the Send as SMS feature won’t be triggered, leaving the texts unsent!
How To Disable iMessage on iPhone
iMessage can be turned off in two ways. If you still have your iPhone, make sure that it has the SIM card in place and visit Settings -> Messages!
Tap the first knob, next to the iMessage field, and turn the service off! That’s it; your done!
You can now remove the SIM card from your iOS device and use it with your new smartphone.
Deregister From iMessage Online
If you don’t have your iPhone anymore and forgot to disable iMessage, you can deregister online via Apple.com.
Start the unregistering process by providing your phone number. You’ll receive a confirmation code from Apple via text message. Provide it at Step 2 and hit Submit! That’s it, your number is now officially deregistered from the iMessage service and iPhone users will be directed to send you regular texts.
Editing Contact Phone Label Doesn’t Help
There are a few sources on the web that recommend changing your contact’s Phone label to avoid sending iMessages, if that particular contact has left the Apple community. However, we can confirm that it’s only a myth because editing the label from iPhone to mobile, work or anything else won’t influence your device when deciding to prioritize using the free built-in messaging service!