Businesses have been warned to make sure their Private Automatic Branch Exchange (PABX) phone systems are secured, as international fraudsters are able to hack into such systems and rack up phone bills running into the hundreds of thousands.

The Telecommunications Carriers’ Forum (TCF) has issued a release saying PABX fraud increased four-fold during 2010, with an estimated 30 to 40 New Zealand companies being hit by hackers every month.

PABX fraud involves hacking into an unsecured phone system, then redirecting internal DDI calls to an external international number.

"Security of your PABX is easily as important as the security of your PC,” says David Stone, CEO of the TCF.

"It’s relatively easy to defraud you of thousands of dollars if you haven’t made your system secure.”

Stone adds that while incidences of PABX fraud have decreased this year, the risk may be heightened for the duration of the Rugby World Cup.

"With so many tourists expected to visit New Zealand, international fraudsters may take the opportunity to target New Zealand for PABX hacking during this time.”

Go here for advice on preventing PABX fraud.