New Unlicensed Mobile Access (UMA) technology, that allows cell phones to automatically switch between regular wireless networks and WiFi hotspots is becoming a popular trend among service providers.

UMA-equipped phones will be able to sense WiFi signals, and seamlessly switch a call onto a cheaper VoIP connection whenever a hotspot is within reach. Naturally, once a user leaves that hotspot, they are automatically switched back on to a normal cellular network without any interruption in their current call.

This kind of technology is designed to improve poor mobile coverage in some homes and apartments, while allowing carriers to implement their own wireless VoIP services, and avoid losing too much ground to web-based offerings like Skype.