Question: Why is 555 always used as a fake phone number?
Answer: The 555 number was inducted into the MPAA standards in the 1970's after there was a complaint of numerous prank phone calls from a fake number in a film starring Herbert Gottfried.
Than the heat came and it went to court and ruled that any publicly displayed and non-associated number must be a misc fake number in which the 555 dialing code is always a dud.
If movie makers where smart they would do this:
Make a big hit film (like ghostbusters) WHO YOU GONNA CALL? Ghostbusters...and the famed number would be setup as a hotline that automatically bills everytime somebody calls thus making that phone number a very profitable piece of residual income.
Just some food for thought.