Linphone - Linphone is an internet phone or Voice Over IP phone (VoIP).
Zoho Meeting - Free video conferencing, online meeting, desktop sharing solution from Zoho.
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
FileFlex - FileFlex: Access Share Stream developed and published by Qnext.
Sipdroid - Free and open-source SIP/VoIP Client
Voxox CloudPhone - Get a local or toll-free business number that automatically answers, routes and transfers calls, plus other professional business phone services.