Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Linphone - Linphone is an internet phone or Voice Over IP phone (VoIP).
Sonetel - Sonetel is a communication app that lets you make an international business call at the cost of local calls.
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Facebook Messenger - Facebook Messenger is a faster way to message.
Sipdroid - Free and open-source SIP/VoIP Client