Asterisk - An open source telephony switching and private branch exchange service for Linux.
InsightSquared - #1 for Salesforce.com Pipeline forecasting, profitability analysis, activity tracking: all the small business intelligence you need. Works using CRM data and automatic syncing.
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.
Aviso - Aviso provides predictive analytics software to help sales organizations optimize their performance and exceed revenue goals using machine learning algorithms and portfolio management techniques.
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).
Sidekick by Hubspot - Customer insight integrated with your email tools.