I had a situation a few days ago when my Tesla simply shut down completely, and could not be restarted while I was driving. This was last Thursday during the ATT outage. Fortunately I was able to restart the car enough to park it in a safe parking space. I then was able to go to an adjacent public library with free wifi and use my phone in wifi mode to contact Tesla Roadside assistance. I don't think there is any way to contact Tesla Roadside assistance without a smartphone with the Tesla app, or is there?