Colin app offers simple User Interface and superb audio quality VoIP calls in affordable rates. Colin works on all iOS devices and supports calling over WIFI/EDGE/3G/LTE. In order to use this app end users can register with their mobile number. Key features include: 
 1. Lowest battery usage with highest reliability / stability on App Store. 2. Lowest latency of all IOS softphones. 3. Bandwidth normalization. 4. Voice/Video packet negotiation 5. Bluetooth support. 6. Excellent audio quality, even on older devices. 7. Supports calling over WIFI/EDGE/3G/LTE. 8.Background / multitasking support. 9.  Integration with the native ios contact list. 10. Speakerphone mute and hold.