On Sept 30 the Canadian Radio-television and Telecommunication Commission launched a national Do Not Call list.
You can Register Online or phone 1-866-580-DNCL (3625). Registering won't stop all telemarketing calls. Charities, political parties, and so-called market research firms can still call. Presumably because they are not trying to sell you something. Telemarketers making calls on behalf of American companies phoning from outside of Canada are not required to register with the Canadian DNCL.
If you have done business with a company in the last 18 months or inquired about a product (if they managed to trap you on the phone and you answered some questions for example) you are considered to have a relationship with that company and they are exempt from the DNCL. However most companies are required to maintain an internal do not call list and you can ask them to put you on their list.
The DNCL gives telemarketers 30 days to take you off their lists and you have to re-register every 3 years.