AstraChat - Direct XMPP & VOIP Client - AstraChat is a standalone and lightweight Jabber (XMPP) client application with VOIP calling that connects directly to your XMPP server without any proxies in-between.
AstraChat is always connected to your XMPP server in the background and provides you with immediate push notifications of new messages
Cheap Calls - XonXar App - Xonxar finds the cheapest rates amongst many VOIP providers and allows you to use them without subscribing with those.
Xonxar offers a simple user interface and the best price performance ratio.
Xonxar allows you to call or send sms from any point in the world and to any point in the world.
Use Xonxar at home, in the office or on the way