Pareteum app for iPhone and iPad
Pareteum combines cellular and WiFi networks to provide you coverage everywhere. Cellular service is expensive and does not always provide the quality coverage where you most need it: home, office, and school. WiFi is everywhere, even the hard to reach areas that many times cellular coverage cannot hit.
With Pareteum, every WiFi connection works just like a cellular tower. Your phone will automatically connect to any approved WiFi or cellular networks, providing you a quality connection everywhere. Now calling and messaging can be done nearly everywhere!