GREENSBORO, NC -- It's a typical afternoon, you're looking at Facebook, maybe watching TV, when you hear a knock at the door.

You get up and look through the peep hole to see what looks like a salesman who says he saw the alarm sign in your yard and wants to ask you about it.

That conversation could cost you. Lechelle Yates, an investigator with Greensboro Better Business Bureau says your alarm sign is a lure, “One thing the BBB is seeing is that unscrupulous alarm sales companies are looking for those signs. They're a beacon that say you already have an alarm system. Let me see if I can get you to change.”

Sometimes the salesperson is claiming your old alarm company is going out of business and you need to sign a new contract with the new company.

But before you do anything, call. “Here in the south, we're very polite. But I'll tell you a scrupulous alarm system sales person is not going to care if you want to take a minute and call and get that information to confirm who they are. They might actually encourage it.”

In North Carolina, the company, the individual and anyone involved in alarm sales must be registered. So to weed out the real from the fake - you can always ask for the registration card or call the Alarm Systems Licensing Board 919-788-5320.

And one more note, with door to door sales, you have a three day window to cancel the services or product.