I saved an email from a long time ago about what to do with with these automated calls. Don't know if it really works but I guess it is worth a try.
What you can do after answering, if you notice there is no one there, is to immediately start hitting your # button on the phone, 6 or 7 times, as quickly as possible This confuses the machine that dialed the call and it kicks your number out of their system. Gosh, what a shame not to have your name in their system any longer !!!
From Winnipeg MB, These clowns just called my number asking about that very same thing, I hung up, and was immediatly phoned back by 3 more telemarketing calls within 4 mins
How did they "retrieve" your number? They didn't. The way they work iswith an automated dialer - their computer just starts at any given area code and dials EVERY possible permutation and combination of #s (since it's cheap to do) until they've covered EVERY number. You are presuming they actually do any research or targetting. They don't. It's just a shotgun pattern to hit everyone. I DO wonder what happens when they call to mention a free Orlando, Florida vacation and they are calling people who live in Orlando, Florida?