Kollbox app offers simple User Interface and superb audio quality VoIP calls in affordable rates. Kollbox 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. Exceptional voice quality. 4. Bandwidth normalization. 5. Voice/Video packet negotiation 6. Bluetooth support. 7. Excellent audio quality 8. Supports calling over WIFI/EDGE/3G/LTE. 9. Background / multitasking support. 10. Integration with the native iphone contact list. 11. Speakerphone mute and hold.