PTTJapan.

The days of long telephone bills resulting from expensive international calls are over.
Cheap Calls: PTTJapan is the best voip app solution; save on your mobile phone costs right away, by using this Mobile voip cheap calls app to make cheap calls to national or international destinations!

PTTJapan is a mobile dialer 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.

Features :-

PTTJapan uses SIP protocol to handle the outgoing calls.
PTTJapan run Behind NAT or private IP.
User Friendly Interface.
Auto Sync of Balance.
Real Time Sip status messages.
Call History.
Loud Speaker.
Address book integration.