Jasmin SMS Gateway - Jasmin is a very complete open source SMS Gateway with many enterprise-class features such as:
Chatfuel - Chatfuel is the best bot platform for creating an AI chatbot on Facebook.
Kannel - Open Source WAP and SMS Gateway
Landbot - An intuitive no-code conversational apps builder that combines the benefits of conversational interface with rich UI elements.
Bulk SMS Services - Sending Bulk SMS to the customers will engage the customers with your business and new offers.
ChatBot - Easy to use chatbot platform for business