Be on-guard for fraud at your front door. Burglar alarm system companies hire college students and recent grads to walk neighborhoods selling their service – but BBB warns some of these door knockers are unscrupulous.These deceptive door knockers may con you in several ways:They may state they’re with your current alarm system and want to offer you an upgrade or to even replace your system. What you’re really agreeing to is a whole new system with a new long-term contract, often at higher rate. And you could be stuck with a contract with your current company as well.The sales person may state your current alarm system company has gone out of business and they’ve taken over. And you have to buy all new equipment and sign a new contract that’s long term and often more than your current system. Again, you could be stuck with a contract with your current company as well.If you don’t have a system, the sales person may make you a limited time offer and say, “You have to act now!” They may even tell you equipment is free. BBB has seen strings are attached – to get the free equipment you have to sign a long term and expensive contract for monitoring. But you won’t realize it until after you sign the new papers.BBB has learned door-to-door sales are actually pretty lucrative – a sales rep can make $1500 for every contract they convert. If they get just one person a day to change systems, they can make $45,000 in just one month. It’s no wonder alarm system sales attracts college students who want to pay off debt.Nationwide, consumer complaints ranked in the top 25 of the 3500 business categories BBB tracked in 2016.An industry spokesperson says door knocking is a very effective sales technique, so trustworthy and not-so trustworthy sales people may knock on your door. So here’s how you can protect yourself:In North Carolina, anybody engaged in the business of alarm systems – from the seller to the installer – must be licensed - including the company. So if you’re interested in the sales pitch, the first thing you should do is ask for:Contractor's nameStreet address (no P.O. Box)Telephone numberContractor's license numberState that issued the licenseName under which the license is filedThen call the state licensing board and check out the seller and the company.You should also call your own alarm system company to double check the upgrade offer of if they have in fact gone out of business. This may seem rude but the trustworthy sales people won’t be offended if you do your homework.If you do fall for the sales pitch, you do have three days to cancel.BBB has screened and monitors Accredited burglar alarm system companies so you can trust them. Click here for a list of Accredited Businesses.