Here in Wisconsin, as in many states, we have a "no call" registry, wherein you register your phone number(s) and the state then issues a "no call" list to telemarketers who are then supposed to studiously avoid calling, under threat of legal action by the State of Wisconsin.
I duly registered all my household phones.
The first thing I found out is calls from pollsters, political parties, businesses you have done business with and charities are not included in the list of organizations forbidden to call. So, mid-dinner calls from the Republicans, various fire and police fundraisers, etc. Not to mention dunning calls on late bills, an unavoidable occurrence in the age of Osamanomics.
Next, the telemarketers learned how to fox Caller ID with bogus phone numbers. This is easy to do, seeing as the people who designed the Caller ID system didn't bother to think past "we can charge for this service!" back when. If you are going to have Caller ID at all, make it universal and un-hackable, or don't bother.
I just got two calls from an Ohio number - (234) 512-3451 - a number that when dialed gives "Your call cannot be completed as dialed. Please check the number and try again." When they called both times, there was dead silence and then a hang up. Harassment?
I've taken to keeping Pandora up on my desktop, tuned into a '60's-'70's oldie playlist. Dunning and political calls get "Please hold" and then whatever Pandora has up at the moment until they hang up. One caller responded to the lyrics from "San Francisco" with "I hear music" before giving up.
The newest proposal out of Madison would add text messages to cell phones to the no-call registry. I wonder how long it will take some hacker to fox that.