MessageBird Chat API - Connect with your customers through different messaging apps
Kannel - Open Source WAP and SMS Gateway
Voiceflow - Build voice apps in your browser without coding
Ozeki NG SMS Gateway - Ozeki NG SMS Gateway is a powerful, reliable and flexible SMS Gateway application.
Twilio Notify - One API to orchestrate notifications across SMS, push & more
KAPSYSTEM - KAP Computer Solutions Pvt. Ltd.,