Dialogflow - Conversational UX Platform. (ex API.ai)
Burner - Disposable phone numbers -- now with MMS photo support
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Hushed App - Hushed App will allow you to receive a Secondary Phone Number for Private, Long-Distance...
Botpress - Open-source platform for developers to build high-quality digital assistants
Numero eSIM - Numero eSIM is a phone-number app that makes voice and data possible anywhere in the world, for free.