Cool, thanks. I just set this up, will try it later. I do have separate cell service for the watch. But right, as Ken said, make sure you have a cell signal if you have no backup device with you.
Last week I did something beyond stupid. New Apple Watch, still don't know what I'm doing, so..........I got out of the car at a rest stop halfway on my 150-mile weekly commute to work. Left the key card and iPhone in the car, phone turned off. Rest stop at a remote location with historically variable cell reception. I did have a cell signal on the Tesla and the phone when I stopped so not worried but didn't check the Watch reception. It's 20 degrees F, didn't bother to take my jacket, go into the rest stop, come out, and the Watch has no cell signal to open the car. Why didn't I take the phone/key card? Because I'm an idiot, that's why.
So I check with the truck drivers. They have AT&T with a cell signal. But not my watch. I have a First Net AT&T account so maybe it's that, or maybe I just don't know how to properly use the watch. So now what? I'm 75 miles from home locked out of the car in the cold. So I decided to call my wife and have her try to remotely open the car from her Tesla app. That or she has to drive 75 miles to bail my ass out. Now I have to borrow a phone from a good Samaritan. Easy enough, call my wife, not sure I remember her number we have had for 20+ years because I never dial the actual number, but then also realize she is not going to answer a call from Joe Samaritan, so I leave a message. No reply. Joe, being a smart Samaritan, suggests sending a text, more likely to see that. Eventually, she calls Joe and figures out how to open the car remotely. Meaning her AT&T signal to the car was functioning. Problem solved, idiot. Point is, be sure you have a cell signal because Bluetooth does not connect from the Watch. More importantly, don't be an idiot. I know, I've tried that, not too cool........