Apple Watch Series 6 NumberSync Resolved / "get the 5-digit code" Message / Corporate Plan

For 2 days I couldn't sync my new Series 6 Apple Watch, spending hours with AT&T tech support. I finally resolved the issue. Things to know:

• The watch must be set to factory setting. If you're replacing a prior watch, don't restore from a previous backup when setting up your watch. That somehow overwrites needed information with the watch, such as the software SIM, EIME or other cell data. This was more core problem.
• As soon as I did a full Reset as a new watch (from the Settings on the watch), it connected to my ATT NumberSync plan immediately. On the watch, go to Settings->General->Erase all Contents & Settings.
• When it restarts, select "Setup as a New Watch".
• After connecting to NumberSync, don't try restoring the watch to a backup. You'll overtire all the Cell data and lose your numbersync.
• The *only* way to associate the watch to the number sync plan on your phone is through the Apple Watch App on the iPhone. Don't try using AT&T's website for "Sync a Wearable". That's for non-apple devices.
• The AT&T website will ask for a "5 digit code". There is none for the Apple Watch. This is for Android devices. Like my last bullet point, you need to use the Apple Watch app on the iPhone.
• The iphone Apple Watch app gave me an error accessing the AT&T sync page. That was because my watch was restored from a previous backup. When I reset/setup as a new watch, the iPhone app run smoothly without error
• My iPhone is on a corporate plan which doesn't support Apple Watch. The workaround is to create a personal AT&T plan, then associate the phone number of the iPhone with your personal plan. The phone remains on the corporate plan for billing purposes. There's no need to contact the plan owner for a password or a code, which is what AT&T support will ask if you call them.
• Your personal phone plan will be billed for AT&T's NumberSync plan, currently $10/month
• Once the iPhone's cellphone number is associated with your personal plan, the Apple Watch app will associate the watch to NumberSync.

Hope this helps.