Apple Watch 3 No Sim No Connection

Follow the instructions here to set up the built-in cellular feature on Apple Watch Series 3 (GPS + Cellular):

• Set up and use cellular on Apple Watch Series 3 (GPS + Cellular) - Apple Support
• Use Apple Watch with a cellular network—Apple Watch Series 3 (GPS + Cellular) only

Note that a service plan is required for your iPhone that specifically includes support for Apple Watch Series 3 (GPS + Cellular), including the carrier activating the device on the plan. An activation fee and ongoing monthly cost may apply:

Apple Watch - Carriers - Apple

If you still need help, then, in the first instance, I suggest that you contact your cellular carrier for further assistance.Depending on your carrier's advice, if you then still help, contact Apple Support, make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance:

• US: Apple Watch Service Answer Center - Apple Support
• Elsewhere: Apple - Support

More information:

Set up your Apple Watch - Apple Support

You don't seemed to have read the Terms of Use when signing up here.

FYI, this is user to user technical forum, users (not Apple employees) like me volunteer our time to help other fellow users. Apple provides the forum but they do not take part here.

If you want Apple support use the link at the top of the page Contact Support.

Please understand this is a peer support forum, so we can share our experience but we can’t speak for Apple, and it is unlikely any Apple employees will read this thread

You mention AT&T so I assume you are somewhere in USA. Your Apple Watch Series 3 must be still within its warranty period, and has a long standing problem which has already defied two visits to the local service depot. I suspect you may have bought the watch through AT&T so there is now an opportunity for AT&T and Apple at a local level to engage in finger pointing to push responsibility onto the other side.

My advice is to step back from the technical problem for a few minutes while you review the original terms of supply. Prepare a 1 page summary of the efforts so far. Try to establish who is responsible, where your contractual rights lie under the warranty and how you go about enforcing your rights. Check your rights under your local consumer “lemon” laws. When you have all the facts lined up you are in a position to make one final attempt to get the problem resolved. Make sure they know this is the third and final attempt with 2 strikes already down, but Be Nice to the workers you contact and try to avoid making them feel they have lost face. They have rules laid down and limits on their authority so you might have to have the problem passed up the food chain.

In the worst case you need to have the warranty anniversary clear in your mind, and make sure you leave a break point with adequate margin if it is necessary to escalate this to AT&T or Apple corporate headquarters.

Just trying to be helpful. Good luck.