The popularity of dual-mode VoIP handsets is set to drive strong growth in the market over the next two years, according to a survey.

By 2009, 30 per cent of mobile users will have a handset which supports VoIP over Wi-Fi as well as being able to make traditional mobile calls, reported Infonetics Research.

This means there will be a seven per cent rise from the current level of adoption over the next two years.

However, there are still some roadblocks which providers need to overcome along the way as Phillip Redman, a Gartner analyst told Techworld: "Most enterprises are hesitant to put in voice over wireless because it means adding more access points to add capacity and coverage."

Nevertheless, VoIP-compatible phones are providing strong competition to mobile network-only handsets, with Infonetics predicting the take-up of these single connection phones is set to drop by 11 per cent over the next two years.

Dual-mode handsets are able to switch calls seamlessly between mobile networks and VoIP PBX extensions when they move within range of a compatible wireless network, allowing users to benefit from the cheaper call costs of VoIP.