Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Voiceflow - Build voice apps in your browser without coding
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Alexa Skill Kit - Effortless Alexa Skill development with AWS Lambda
Plivo - Plivo simplifies your customer engagement.
API to bot - Convert your API to Alexa skill or Google Home app in 5 mins