Use Dual SIM with Apple Watch GPS + Cellular models

If you set up Dual SIM on your iPhone XS, iPhone XS Max, or iPhone XR or later, you can add both cellular plans on your Apple Watch Series 4 or later, as long as each plan is eligible and from a supported carrier.     

You can set up one plan when you set up your watch for the first time. Then you can set up your second plan later in the Apple Watch app:

1. On your iPhone, open the Apple Watch app.
2. Tap the My Watch tab, then tap Cellular.
3. Tap Set Up Cellular or Add a New Plan. If you didn’t add your first plan during setup, you can add it here.
4. Follow the onscreen steps to choose the plans that you want to add to your Apple Watch. Each cellular plan will be billed separately. If you need help, contact your carrier.

You can add up to five cellular plans to your Apple Watch. However, your Apple Watch can only connect to one at a time. 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.