Sounds like they'd like to come into your home, case the place -put in a bogus alarm system. Slap a sticker in your home to identify you to their collegues. And take the stuff you've worked hard to get.
"Hi, this is Kevin from Home Security Group. We're looking for advertisement opportunities in your area, and we were wondering if you'd like a free home security system in exchange for putting a sign in your yard."
uhh. That would be a "no". I'd rather not get a fake system and have you steal my stuff. Besides, why are you calling my cell and not my landline?