iwatch ultra it doesn’t work in Mexico Telcel

Telcel DOES support Apple Watch in Mexico. Where did you purchase the watch? If bought it anywhere other than the US, Canada, Mexico or Puerto Rico, you bought the wrong watch and you won't be able to use a carrier in Mexico. There are two models of cellular Apple Watches. Watches for the US, Canada, Mexico, Puerto then watches for the rest of the world.

Here is the list of carriers supporting Apple Watch throughout the world --> Apple Watch - Carriers - Apple

Again, if you purchased your watch outside the locations I listed above, that is an issue.

This Apple webpage says Telcel supports the Apple Watch.

Apple Watch - Carriers - Apple

If you purchased the Apple Watch Ultra in Mexico, the United States, Canada, or Puerto Rico, then it should work on the Telcel network, just like any other Apple Watch purchased from one of those countries.

What is the model number of your ultra watch?

Identify your Apple Watch - Apple Support

If it is a model A2622, it should work with Telcel.

If it is a model A2684, it will not work with Telcel.

For more info, see:

Apple Watch - Carriers - Apple

That's what you've told us. But there is NOTHING we can do to help with your carrier. And we are NOT Apple. We are all users like you on this user to user only forum.

As suggested above, go higher up with Telcel technical support.

I understand you live in Mexico. You didn't answer my question. WHERE was the watch purchased?

Then there should be no issues with cellular service to the watch as long as Telcel is also your carrier for your iPhone. Are they?

Go to a different store with better support.