A hacker recently obtained unauthorised access to the IP telephony 
(VoIP) system of a Perth business, making 11,000 calls costing over 
$120,000, according to the Western Australian police.

The calls were made over a period of 46 hours, the police said, and the 
business only became aware of the imposition when it received an invoice 
from its service provider.

Thieves have always targeted PBX systems by finding numbers used for 
remote calling — for mobile employees or those requiring international 
call access outside of business hours — to make calls at the company's 
expense.

This has in the past been exploited for uses such as routing calls made 
on cheap international phone cards, according to Pure Hacking senior 
security consultant Chris Gatford.

However, police said they were more concerned with the increasing number 
of occurrences such as that in Perth where the thieves gained access to 
users' VoIP network. They have issued a warning to small businesses to 
ramp up their VoIP security.