Five9 - Five9 provides cloud-based call center software for sales, marketing and support.
Asterisk - An open source telephony switching and private branch exchange service for Linux.
Avaya - Avaya is a leading communication platform that provides the complete portfolio of software and services for multi-touch contact center and unfiled communications offered on premises in the cloud or a hybrid.
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.
Verint Workforce Optimization - Manage your workforce and drive performance so you can make better decisions, increase productivity and improve CX via staffing and performance solutions.
freepbx - FreePBX is a web-based open source GUI that controls and manages Asterisk (PBX).