Reporter: Ruwani Perera
The heart of small and medium-size businesses is under attack by overseas fraudsters who are hacking phone lines and racking up huge bills. The phone fraud "business" is estimated to be worth $US80 billion annually.
The fraudsters target PABX phone systems - the type most New Zealand businesses use for features like voicemail and transferring calls - looking for a weakness in the security that will allow them to take over the line. It's believed the crooks make their money by selling phone cards and then re-routing calls they get, via your company's phone lines, all over the world.
How might you know you're being hacked before you get landed with an exorbitant phone bill? All your phones keep ringing and when you attempt to answer the telephone there is no one at the other end. This is a distinct sign that your phone line is under attack.
Phone hacking's not only an irritant for businesses, but also our two major Telco's - Telecom and Telstra Clear. They report attacks happened in March this year, with fraudulent calls coming from Zimbabwe and Somalia.
Telecom report 20 business customers attacked this year and they say they've refunded all of them.
Telstra Clear also report 20 of their customers who are victims. They say they share the financial burden of phone fraud 50-50 with their customers.
When you check your phone bill look for repeated short duration calls to the same number - this could be an indication of an attempt to attack your system.
Never give out technical information about your system to callers unless you are certain who is on the other end of the line.
Use pin numbers which are not predictable - for example last digits of your phone number - or sequential numbers like 1111 or 1234 - and ensure they are changed regularly - especially when employees or contractors leave the business.
Treat your phone security as you would your computer firewalls and anti-virus applications.
For more information - check with your Telco provider what else you can do to protect yourself from these attacks.