Companies across Northern Ireland are losing out on thousands of pounds due to widespread phone scams, it has been claimed.
Firms are being scammed by as much as £10,000 due to 'phone hacking'.
According to telecoms firm Rainbow Communications, the number of criminals breaking into phone lines remotely and racking up huge bills is now on the rise across Ulster.
The PSNI said it was aware of the crimes.
"We have received reports and are investigating," a spokesman said.
David Beatty of Rainbow said it was urging companies to be vigilant.
"We are all too aware of the term ‘phone hacking’ in the media, but this type of phone hacking is a real and serious concern for businesses in Northern Ireland," he said.
"Fraudsters are making thousands of international or premium rate calls resulting in substantial costs at the expense of the unsuspecting company.
"One Belfast firm lost £10,000 in just one weekend while one in North Down was scammed to the tune of £3,000."
He said scams could have a "detrimental effect" on companies here.
“This type of activity is linked to organised crime and the international criminals are increasingly targeting UK companies," he said.
"There have been cases of businesses losing tens of thousands of pounds."
According to Mr Beatty, tips to avoid such attacks include restricting numbers staff can dial, barring "unnecessary call destinations such as international or premium rate numbers" and reviewing call logging reports to spot any bumps in the number of calls being made.