A new report from Juniper Research reveals that mobile VoIP services will grow fast in developed markets because of the direct connection between 3G rollouts and the uptake of mobile VoIP services. The firm said there could be 100 million mobile VoIP users within two years.

"By 2012 we expect significant uptake of mobile VoIP in its various different flavors", said Anthony Cox, senior analyst with Juniper Research. "By that date mobile VoIP will be available over both 3G and WiFi networks. We also anticipate that several more traditional operators will have joined 3UK and Verizon  (NYSE:VZ) in the U.S. and developed relationships with mobile VoIP players such as Skype."

Juniper further believes that alliances between mobile VoIP players and operators may provide best best way for incumbent operators to address the threat that mobile VoIP presents to their circuit-switched voice services. The firm predicts that a high percentage of mobile VoIP calls will travel over WiFi networks, thus bypassing operators' networks altogether. Juniper believes this trend will result in $5 billion in lost revenues by 2015.