The spread of consumer VoIP is being hampered by a lack of understanding, new research has found.

A report by analyst firm Yankee Group has discovered that a large proportion of consumers don't know that VoIP services such as Skype can be used with standard handsets. The research said 35 per cent of VoIP-aware households in the US don't know that the services can be used with a "regular telephone".

The report concluded that the consumer VoIP market remains immature, despite a number of big names recently becoming involved in the sector.

Yankee Group also noted that marketing strategies used by cable companies - which sell VoIP packages as purely free or cheap calls, rather than drawing consumers' attention to the VoIP aspect of the service - is hurting consumer awareness.

In the UK, ISP Wanadoo is now claiming to be the number one consumer VoIP provider, with 80,000 users, compared to BT's 50,000. Both, however, are a long way from catching market leader Skype, which now has more than 50 million users worldwide.