Deregister iMessage on your iPhone or online
If you switched to a non-Apple phone and aren't getting SMS/MMS messages, you might need to deregister iMessage.
Deregister iMessage on your iPhone
If you still have your iPhone, you can deregister iMessage with these steps:
If you transferred your SIM card
Make sure that you're connected to your cellular data network.
Tap Settings, then tap Messages. Turn off iMessage.
Tap Settings, then tap FaceTime. Turn off FaceTime.
Deregister iMessage online
If you don't have access to your iPhone, you can deregister iMessage online. After you complete deregistration, your phone number is removed from iMessage services. You should be able to receive text messages straight away but it might take a few hours for some Apple devices to recognise that you're not using iMessage when they send you a message.
If someone sends a message using iMessage to your Apple ID, you’ll receive it on your other Apple devices. If someone sends a text to your phone number, you'll get the message as an SMS/MMS only on your phone.
