Answered their call, definite scam. I asked them where are you located, and it seemed they did not know how to respond, read Anon post above. Most likely, they get your address and information to hook you in by offering a free security system, then need a deposit retainer for either goodwill/to pay for the travel and/or parts and materials, then they disappear. BEWARE!
They called my cell phone at 12:15 PM PDT, 3 October 2013. (They called my home phone once before last August. See my Anon 13 Aug 2013 note below. The home and cell phones are in the same area code.)
I did not answer, and they did not leave a voice mail. I will report them to DoNotCall.gov, assuming it isn't shut down with the rest of the government.
Warning:
I am noticing an increasing number of "spam" phone calls with caller IDs in my local area code, or sometimes from a nearby area code. I think it is a new trick to get people to answer - if the area code is familiar, you may be tricked into answering the spam call.