MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Sinch - Sinch is a powerful voice and messaging SDK that lets you bring your apps to life with VoIP and...
Plivo - Plivo simplifies your customer engagement.
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
smooch - Smooch connects your business software to all the world’s messaging channels for a more human customer experience.