Before you remove the SIM card from your iPhone
Make sure to turn iMessage off before you remove the SIM card from your iPhone. Otherwise, your SMS/MMS messages could continue going to your old iPhone instead of your new phone.
Turn off iMessage
- On your iPhone, go to Settings.
- Tap Messages.
- Set iMessage to Off.
Restart group chats
If you're in any group chats with friends who have iPhones, to keep getting their messages, start a new group chat. Your friends can also start the new group chat.
Already removed the SIM card from your iPhone
If you no longer have your old iPhone or already removed the SIM card, request that Apple deregister your phone number with iMessage.