Joe,
With all due respect to your mentor.... you can do whatever you want, technically... I say this because:
Even though we all wanna be great directors

we are not there yet. So technically all the rules can go right out the window. Since we are not "Hollywood", we don't really have anyone to answer to but ourselves. Can you imagine the filmmaker of "Run, Lola, Run" explaining their idea to someone? The point is, you have to make whatever it is you are going to do
work. You have to come up with a way, that doesn't bore people or stretch reasonable plausibility. If you can figure out a good way to do that, who's to say you can't? You can almost do
whatever you want. But what you do has to be better than the other guy, has to work better than the last place you saw it done. My dad used to say: just because it hasn't been done before, doesn't mean it won't work.
...and speaking of the phone thing being done before, two movies:
"Phonebooth" and
"Cellular".
You just have to do better than the other guy....
-- spinner
