Asterisk - An open source telephony switching and private branch exchange service for Linux.
HubSpot - Grow Better With HubSpot: Software that's powerful, not overpowering. Seamlessly connect your data, teams, and customers on one CRM platform that grows with your business.
FreeSWITCH - FreeSWITCH is an open-source media application designed to support popular protools such as SIP and WebRTC and provides a platform to develop voice and video applications.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).
Marketo - Marketo's powerful marketing automation software helps marketers master the art & science of digital marketing to engage customers and prospects.