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, even on older devices.
8. Supports calling over WIFI/EDGE/3G/LTE.
9.Background / multitasking support.
10. Integration with the native ios contact list.
11. Speakerphone mute and hold.