MessageBird Chat API - Connect with your customers through different messaging apps
Clearstream - Clearstream is a SMS marketing and online texting software.
PHLO by PLIVO - Visually integrate Voice and SMS into your apps in minutes.
Swift SMS Gateway - SMS Gateway is your bridge between the Internet and the world of cell phone SMS text messaging.
Voiceflow - Build voice apps in your browser without coding
Maytapi - Serverless Whatsapp Api with Chat and Agent support.