With the Updated Vopium app for Android which currently available in the Android Market you can make Free International Calls to other Vopium,Gtalk and Skype Users who are online and low rate calls to Non-Vopium users through 3G and Wi-Fi. You also get free 15 Minutes of Free International Talk time via 3G and Wi-Fi. The only let down is that you have to be connected to the Internet while making calls as the calls are made through the Vopium Servers.
To get the free 15 minutes of International calling you will have to register.To register just visit this site.Enter the info that is asked and you are done.To make free calls you will have to enable the usage of 3G and Wi-Fi in VoIP Settings.
Using Vopium you can also chat with your friends on Google Talk,Skype,AIM,ICQ,Windows Live Messenger,Yahoo and Twitter.Vopium is not only available for Android but also for other platforms such as Symbian,java,iPhone,Blackberry and Windows Mobile.