While this doesn't help your search for software (and I want to see the results if you do find what you're looking for), I'd say get a cordless phone with answering machine that can check the messages from the handset. Then you a)let the answering machine screen your calls and b)only have to reach over to check the messages to see if it's someone you want. Telemarketers most often don't leave messages. If you want to go one step further, get a baby monitor and put it next to the answering machine (which I assume you don't want downstairs) so you can answer your friends immediately when they call.

-Zeke