receiving a fax call from this number, tried to call the number back and it states "call can not be completed as dialed".

Unsuccessful in contacting them to remove our number from their autodialer list, contacting our phone service provider to block the number.

A call about some sort of software conference that I did not subscribe to or give my number out at.

this is a fax number, on the fax that we received they gave us a phone number to call to remove us from their list, which is (416) 544-4317

however, the operator indicated that this phone number doesn't exist, so there is no way to stop them

and i am on the DO NOT CALL LIST
what they are doing is totally unethical

For those that have pressed buttons, I'd be sure to check your next phone bill to be sure you're not later being charged for the call - like a $50 call from Nigeria or the Bahamas or something! For those asking about the Do Not Call Registry, I'm sure the caller wasn't a charity, political group or survey taker (the allowed exceptions), but I'm equally sure the caller doesn't CARE about the DNC list. They're probably criminals - and criminals don't care about the list!!

Just a bad business.