A few months ago, we posted a story about popular frauds that small business owners and managers need to look out for in everyday operations. These usually involve either supplies or websites, but now there’s something else you need to be aware of—and it’s an old-fashioned telephone scam: Hackers using landlines to run up your phone bill. That’s right, landlines!

According to the New York Times, the scam goes like this:

Hackers sign up to lease premium-rate phone numbers, often used for sexual-chat or psychic lines, from one of dozens of web-based services that charge dialers over $1 a minute and give the lessee a cut. In the United States, premium-rate numbers are easily identified by 1-900 prefixes, and callers are informed they will be charged higher rates. But elsewhere, like in Latvia and Estonia, they can be trickier to spot. The payout to the lessees can be as high as 24 cents for every minute spent on the phone.

Hackers then break into a business’s phone system and make calls through it to their premium number, typically over a weekend, when nobody is there to notice. With high-speed computers, they can make hundreds of calls simultaneously, forwarding as many as 220 minutes’ worth of phone calls a minute to the pay line. The hacker gets a cut of the charges, typically delivered through a Western Union, MoneyGram or wire transfer.

The Times reports that some small businesses have seen their bills run into the hundreds-of-thousands due to the scam. While many of them have been table to talk down these figures to either manageable amounts or nothing, some have not been so fortunate, like Bob Foreman of Foreman Seeley Fountain Architecture in Norcross, Ga. Their phone bill came to $166,000 in one weekend last March. And now also includes $17,000 in late and cancellation fees. TW Telecom, their carrier, isn’t backing down either, claming it’s the company’s fault, not theirs.

Either way, whoever’s to blame, this isn’t something you want to have to deal with.

How to prevent this from happening to your business

The advice is fairly simple: Turn off call forwarding and set up strong passwords for your voicemail and long distance calling systems. Strong passwords, for those who may not know, are case-sensitive, and include letters, numbers and symbols.

Bottomline: Treat your landline telephones (as strange as it sounds) like anything that might be attached to the internet.

(Feature image: Oona Räisänen via Flickr)