Asterisk - An open source telephony switching and private branch exchange service for Linux.
Pony Express HQ - Pony Express HQ is an SMS text message marketing for small businesses, real estates, clubs, communities, dispensaries or non-profits. Send and receive text messages and images online with the large group of customers. Group texting app no reply all.
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.
SimpleTexting - SimpleTexting offers SMS and text marketing services for companies of all sizes.