1. Open “Settings” on the iOS device and tap on “Messages”.
2. Scroll down and tap on “Receive At” which is usually followed by a phone number or email address.
3. Tap the “Use your Apple ID for iMessage” button at the top and sign in.
This ensures your Apple ID is being used for iMessage, you’ll want to make sure the phone number and email address you intend to receive iMessages at are correct.