Actually you should never answer unrecognized numbers... once you answer then the scammers knows it's an active number with a real human attached to it...
Your phone number can then be sold to other scammers because these people do not care about Do No Call registries as they spoof their phone numbers and are therefor untraceable
Just got a call from 301-804-9454. Got two last week and this time I answered and the "I'm from Police Chiefs of America" and was looking for someone else. Let him know that wasn't me and he started in on his speech. After about 10 seconds told him not interested and informed him not to call here again and hung up on him. Hopefully from my tone of my voice he won't call again.