While you can't directly add a new cellular phone number to your Apple Watch independent of your iPhone's cellular plan (unless you set up a separate plan, covered below), you can add phone numbers for use with your Apple ID and iMessage/FaceTime on your Apple Watch.
Here's how to add contact phone numbers for iMessage/FaceTime on your iPhone, which will then sync to your Apple Watch:
- On your iPhone, open the Settings app.
- Tap on your name at the top of the Settings menu.
- Tap "Name, Phone Numbers, Email".
- Tap "Edit" next to Reachable At.
- Tap "Add Email or Phone Number."
- Choose "Add Phone Number."
- Enter the phone number and tap "Next". A verification code may be sent to the number.
- Enter the verification code if prompted.
These steps add the phone number to your Apple ID and allows it to be used for iMessage and FaceTime. Your Apple Watch will then be able to use this phone number for these services.
Using Cellular on your Apple Watch (if applicable):
If you have an Apple Watch with cellular, it shares the same phone number as your iPhone's cellular plan (through your cellular carrier). You cannot add a separate phone number directly to the Apple Watch cellular plan itself unless you are specifically adding a family member to a Family Setup.
Family Setup:
With Family Setup, you can set up an Apple Watch for a child or older adult who doesn't have their own iPhone. In this case, the Apple Watch does get its own phone number and cellular plan. This is set up through the Apple Watch app on your iPhone. Contact your cellular carrier for plan details.
In summary, the Apple Watch shares the phone number of the linked iPhone for cellular service. You add phone numbers associated with your Apple ID through your iPhone's settings, which will then be used for iMessage and FaceTime on the watch. For Apple Watches with cellular, the watch shares its phone number with the iPhone, unless Family Setup is used, in which case, the watch gets its own number.
