Twilio - Brings voice and messaging to your web and mobile applications.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
RingCaptcha - Onboard and verify mobile users with a single SMS
Sinch - Sinch is a powerful voice and messaging SDK that lets you bring your apps to life with VoIP and...
Spring Edge - Spring Edge offers voice, messaging and authentication API's for business applications.