we check the call display, and dont answer if its unknown or blocked or looks like some 1800 marketing type #.
our friends know we have a baby daughter, and often cant answer anyway so they can always leave a msg.
but if they should happen to get me, if its a survey I just say no thanks I dont do surveys as I hang up, if its a charity I tell them I have specific charities and dont give ones who solicit by phone. (often the charity hires telemarketing companies to raise money and only a small portion goes to the charity, so Id rather just give to the charity directly)
if its one of those telemarketers who goes into a spiel without giving you a chance to answer I put the phone down and see how long it takes before they realize theyre not talking to anyone.
years ago my mom was a pushover and the charities shared her number, so we screened her calls. I could tell it was a charity if they couldnt pronounce the name and would ask who it was, and from where, and once the telemarketer said it was john, john from vancouver and when I said shes busy, he said 'fuckyou you goof' and hung up.
so since then I didnt have any problem dealing with marketers.