'For the moment, VOIP security does not appear to be at the forefront of IT managers' minds,' said Stewart. 'But it is definitely something people should consider and be prepared for.'

On the other hand, VOIP is also prone to becoming a target for spammers, added Andy Lake, MessageLabs director of partners.

Both experts believe that VOIP is still pretty much a closed structure since almost no company exposes their VOIP system to the Internet. However, by the time companies start publicizing their SIP (Session Initiation Protocol) addresses used in VOIP communications on business cards and Web sites, security will become essential.

'I really don't think people should be deploying VOIP unless they have the necessary security in place,' said Lake 'Even if I haven't heard about any of these abuses actually happening, eavesdropping from a competitive advantage standpoint, could be a major disadvantage for any user.'

Experts recommend the use of such security appliances as firewalls that are specifically designed to filter VOIP traffic for suspicious patterns and drop those connections.