Your Apple Watch will have the same phone number as your iPhone.
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Before you start
- Make sure that you have the latest software on your iPhone and your Apple Watch.
- Check for updates to your carrier settings.
- Make sure that you have an eligible cellular service plan with a supported carrier. Your iPhone and Apple Watch must use the same carrier,* and you must be within your carrier's network when you set up cellular on your watch.
- If you have an enterprise or corporate cellular service plan, check with your company or carrier to see if they support this feature. Pre-paid accounts and some older accounts aren’t currently supported. To make sure that your account is eligible, contact your carrier.
* An Apple Watch that you set up for a family member can use a different carrier than your iPhone uses.
Set up cellular on Apple Watch
You can activate cellular when you first set up your Apple Watch, or when you set up a watch for a family member. During setup, look for the option to set up cellular, then follow the onscreen steps.
You can also set up cellular later from the Apple Watch app:
- On your iPhone, open the Apple Watch app.
- Tap the My Watch tab, then tap Cellular.
- Tap Set Up Cellular.
- Follow the instructions for your carrier. You might need to contact your carrier for help.
You might see a phone number assigned to your Apple Watch that differs from the phone number assigned to your iPhone. The number shown for your Apple Watch is for your carrier's billing or tracking purposes only; your iPhone and Apple Watch share the same number.
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copied from: Set up cellular on Apple Watch - Apple Support