We still get telemarketers calling us late at night. Usually I look at the caller ID and then decide not to answer the phone. Most of my friends and family have their names pop up, but not everyone. So sometimes before five rings and the answering machine picks up I am left trying to parse the phone number. "Do we know anyone from the 507 area code part of the US?
It used to be easier as many of the telemarketers were calling from a 1-800 or 1-888 number. But now some of the services we use call from their too. So our food service or some theater subscriptions don’t get answered and we lose our hard-won seats… again. :o(
Then there is the matter of how to handle the call politely but firmly. I saw this statement on the blogosphere, "Thank you for calling. Can you please hold? <click> I think that might be a clever way to handle these callers. You don’t want to ruin your karma by being overtly rude. But you don’t want to talk to these people either.
How do you handle the telemarketing calls you get?
The Bis Key Chronicles 
I use to be a telemarkerter and I use to do surveys for companies so I know how hard it is when people are extremely rude. You are just doing your job. So when I get a telemarketer I tell them I appreciate their call, but I am just not interested. Then I thank them again for calling and hang up. That seems to let them know, that I know they are just doing their job, but I am not interested.
I don’t get many calls anymore since I am on the national do not call registry. But when I do I am polite and tell the person I am not interested, sometimes I ask them to remove me from their calling list.