cellular not in use on apple watch

I give you an "A" for effort in trying to circumvent how cellular on Apple Watch works when paired to your iPhone, but it's a fail just the same. BobHarris is totally correct and what you thought would work, simply will NOT work. Your watch, which is paired to your iPhone, both on the same Apple ID, which both must be, MUST use cellular from the same carrier as your iPhone. Since your carrier does not support Apple Watch, you'll either have to move to a different carrier or accept that your watch will work as a GPS only Apple Watch.

No.

when paired to an iPhone, the Apple Watch expects to shave the iPhone’s phone number and cellular plan.

When setup via the Apple Watch family plan, it expects that the controlling iPhone will still be in control.

You broke the Apple Watch Family plan control when paired the Apple Watch to your iPhone. It does not matter if both iPhones were the same iPhone, the software does not have a 3rd state that you seem to want.

Typo fix: 'shave' should be 'share'

You choices are:

• Use your Apple Watch as if it were a GPS only model, which will do everything the cellular model will do AS LONG AS your iPhone is nearby, where nearby is generally in the same moderate sized wood framed home. Least expensive.
• Switch your iPhone to a carrier that supports the Apple Watch and pay the equivalent of $10 U.S. per month to add your Apple Watch to your iPhone's cellular plan.
• Keep your Apple Watch Family Plan setup, and use the Apple Watch as if you were a dependent child or aging parent. This mode, as you may have figured out limits what the Apple Watch can do, because it does not have a iPhone it is paired with. The only plus side is you own the controlling iPhone and would not intentionally add additional school time limits to the Apple Watch. But it is not going to be as useful as if you really paired the Apple Watch to the iPhone.

I didn't add option three, which I should have. That said, The OP should be aware that using option 3 would make the following true if used as Family Setup:

"The following features and apps are not available: Medications, respiratory rate, irregular heart rhythm notifications, ECG, AFib History, Cycle Tracking, Sleep, Wrist Temperature, Blood Oxygen, Audiobooks, Remote, News, Home, and Shortcuts."

Those are significant to me, but may not be to the OP.

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