IT managers should not assume that because their data networks are protected, adding voice to their systems will be secure, as well.

'Administrators may mistakenly assume that since digitized voice travels in packets, they can simply plug VOIP components into their already-secured networks and remain secure,' said Stewart. 'However, the process is not that simple.'

'It would be good if in addition to installing specific products that can weed out suspicious VOIP traffic, companies should consider how their VOIP networks play in their overall security efforts, said Matthew Guide, Sales Director for Asia Pacific at SurfControl, a Web and e-mail filtering provider.