4UVoice.

4U Voice is a mobile dialer or application which makes VoIP calls with minimum iOS version support of 3.2 on Apple iPhone, iPad, iPod and it uses the 3G/Edge/wifi Internet connectivity.

4U Voice is developed based on the requirements of VoIP Providers business needs.

Features :-
4U Voice uses SIP protocol based for signaling.
4U Voice Supports all codecs.
4U Voice run Behind NAT or private IP.
User Friendly Interface.
Auto Sync of Balance.
Real Time Sip status messages.
Call History.
Loud Speaker.
Hold.
Address book integration.
Compatible with all sip standard switches.
It has very efficient implementation of jitter buffer to play voice smoothly.
Silent suppression and comfort noise generation has been used to reduce the bandwidth usage, and this makes the dialer more efficient in making VoIP calls.