Of course, AT&T denies this, but they have shown quirks in the past, and the tendency to go way out of line on how their employees behave outside of work.
On an unpaid break, workers should be to do what they wish, within reason. I do understand the manhole issue, but I would think it would be up to the company to provide the alternative, not a burden to be placed on the worker.
To tell someone they can't run their air-conditioning or heat in their car is ridiculous. Trying to enforce such policies would be an utter waste of resources.
Ma Bell, you're killing me here.