I finally found a way to deal with these telemarketers by following . Here's a modified version based on my own experience:
1. Check caller ID and watch out for "Private Name", "Unavailable" and numbers starting with toll-free area codes (800,866,877...) then:
- Either let the voice mail take the call (on the rare occasion that it's a bank or something important they will leave a message)
- Or if you really have to answer, answer with a very firm and angry "Hello!"
2. Remember they usually ask for [Mr. or Mrs. You Last Name]
- Respond with "Whom may I say is calling?". They freak out: "It's just a courtesy call, nothing important, we could call at a better time".
- Tell them "[he/she] is not available". (Use your own gender, they can make a good guess it's you but there's nothing they can do about it!)
- optionally you could ask if they want to leave a message (which of course they never will).
3. Then they'll say "What would the best time to call [him/her]"
- Respond: "the 6th Friday of any month."
-> You won't believe it but this actually works! Once on the phone with you they don't actually think so they'll apologize, thank you and hang up. It's only after they write a memo to call you back that they realized you were messing with them! For better results say "the 5th Friday of the month" unless the month you're currently in does in fact have 5 Fridays.
* If you feel bad for those minimum-waged part-timers doing this, remember that they usually get paid per conversation and you just had a conversation with them ;-)
* Do not call list: I still don't know if this works in Canada, I read once the the do not call list in Canada doesn't work so well. In the US you should say "Please put me on your do not call list" and legally they shouldn't call you back. Saying "Take my number off your list" or "Do not call back" or anything that doesn't mention the do not call list just WON'T WORK!
Source: Wikihow (Which has more articles besides the one I used in dealing with telemarketers).