Asterisk - An open source telephony switching and private branch exchange service for Linux.
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.
EZ Texting - EZ Texting provides SMS marketing solutions to businesses of all sizes.
FusionPBX - FusionPBX is an open source FreeSWITCH GUI.
Textmagic - The all-in-one solution for all your business texting needs - marketing campaigns, two-way SMS chats, reminders, notifications, and internal staff communication.