Asterisk - An open source telephony switching and private branch exchange service for Linux.
SlickText - Slick Text provides businesses and organizations with an easy and affordable platform for text message marketing.
Wazo.io - The UCaaS Platform Built for MSPs
SimpleTexting - SimpleTexting offers SMS and text marketing services for companies of all sizes.
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.
Textmagic - The all-in-one solution for all your business texting needs - marketing campaigns, two-way SMS chats, reminders, notifications, and internal staff communication.