Phone # not associated with iphone

Hello N33dsupp0rt,

Welcome to Apple Support Communities. 

We understand that you’re seeing a message that the phone number is registered to your Apple ID but not to your phone. We are happy to help.

It sounds like you may have switched carriers or recently changed to new phone number. The phone number that shows on your device should also be the same phone number used with iMessage and FaceTime. Please go to Settings > Phone > My Number. We want to ensure that your phone number is displaying correctly. Are you able to send SMS messages successfully with your phone number?

Here’s how to add your phone number to iMessage and FaceTime: Add or remove your phone number in Messages or FaceTime - Apple Support

"Set up your phone number

On your iPhone:

1. Go to Settings > Messages and make sure that iMessage is on. You might need to wait a moment for it to activate.
2. Tap Send & Receive. If you see “Use your Apple ID for iMessage,” tap it and sign in with the same Apple ID that you use on your Mac, iPad, and iPod touch.
3. In the "You can receive iMessages to and Reply From" section, make sure that your phone number and Apple ID are selected.
4. Go to Settings > FaceTime and make sure that your phone number and Apple ID are selected in the "You can be reached by FaceTime at" section.

On your other devices, you can now turn on the phone number that you just set up:

• Turn on your phone number for your Mac
• Turn on your phone number for your iPad or iPod touch"

Here’s what to do if you get an error message when trying to activate iMessage or FaceTime: If you can’t turn on or sign in to iMessage or FaceTime - Apple Support

"Check your device settings

1. Make sure that you’re connected to a cellular data or Wi-Fi network. 
2. If you're using an iPhone, you need SMS messaging to activate your phone number with iMessage and FaceTime. Depending on your carrier, you might be charged for this SMS.
3. Go to Settings > General > Date & Time and make sure that your time zone is set correctly.

Turn off and restart iMessage and FaceTime

1. Go to Settings > Messages and turn off iMessage.
2. Go to Settings > FaceTime and turn off FaceTime.
3. Restart your device:

• iPhone
• iPad
• iPod touch

4. Turn iMessage and FaceTime back on.

Still not activated after a day? 

It might take up to 24 hours to activate iMessage and FaceTime. If the issue continues after 24 hours, follow these steps:

1. Make sure that your device has the latest version of iOS or iPadOS.
2. If you're using an iPhone, contact your carrier to make sure that you can send and receive SMS messages.
3. Make sure you can send and receive SMS. If a prompt appears stating "Your carrier may charge for SMS messages used to activate FaceTime and iMessage", tap "OK" to allow possible SMS charges.
4. Contact Apple Support."

These steps may help. Let us know if you have further questions.

Take care.