XO Hosted PBX - Hosted PBX is a scalable UC solution that uses cloud technology to integrate HD voice & data services, mobility, along with advanced calling
GoToWebinar - Webinar & Online Conference | GoToWebinar
Zoiper - Cross-platform VoIP softphone dialer for SIP and IAX systems
Zoom - Equip your team with tools designed to collaborate, connect, and engage with teammates and customers, no matter where you’re located, all in one platform.
Sipdroid - Free and open-source SIP/VoIP Client
WebEx - Cisco WebEx Web Conferencing, Online Meetings, Desktop Sharing, Video Conferencing