For various reasons having to do with my name being in the phone book with just my initial, and thus my getting bill collector calls for agencies after people with my first initial, I finally sprang to pay for caller i.d. At least those creeps tend to leave a speech on one's answer machine, and I call them and tell them they have the wrong number. If I don't, they don't desist, a hard lesson to learn.
In the last few weeks I've gotten an increasing number of hangup calls, and if I'm right by the phone, I catch the number. I've gotten three from Westchester, DC (Westchester, DC??); one today from Forsyth, Montana, and several over weeks from Los Lunas, NM.
I find this out by looking the numbers up at Zaba or a white pages site.