WhatsApp Business - Communicate more efficiently with your customers
Asterisk - An open source telephony switching and private branch exchange service for Linux.
WATI - No-code chatbot builder for WhatsApp Business
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.
ChatBot - Easy to use chatbot platform for business
FusionPBX - FusionPBX is an open source FreeSWITCH GUI.