Birdstep recently launched SmartVoice, a Mobile VoIP extension to the market leading SmartConnect products for dual-radio SmartPhones with WiFi and cellular capabilities. 
The new client includes Windows Mobile and Symbian support, full re-branding capabilities and a patented mechanism for automatic switching between WiFi and cellular networks.
A mobile subscriber using the SmartVoice client maintains his or her cellular number, while the technology provides voice call continuity, even when WiFi connection is broken in the middle of a call. The client replaces the built-in dialer in the Smartphone, and provides full integration with existing phone features such as the built-in address book for easy dialing. SmartVoice utilize Birdsteps patented technology for seamless roaming.
SmartVoice has been developed by the subsidiary VoiceRoaming Technology AS, a subsidiary that is owned to 55% by Birdstep and 45% by TeleVenture, the people behind Telenor Venture.