Apple is not here. You are just talking to your fellow users.
This is a list of carriers that support the Apple Watch:
Apple Watch - Carriers - Apple
It is up to the carrier as to whether or not they support the Apple Watch, because it requires sharing the iPhone’s phone number with the Apple Watch.
If you do not have a carrier that will support the Apple Watch, it is possible to get all the features AS LONG AS the paired iPhone is nearby.
You can still leave the iPhone at home while you exercise, and when you get near your iPhone, all your exercise data will sync to the iPhone.
If your carrier does not support the Apple Watch, contact them and ask them to support the Apple Watch.