Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
MirrorFly - World's Most Scalable Voice, Video & Chat SDK for Small, Medium & Enterprises
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Plivo - Plivo simplifies your customer engagement.
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
Infobip - A2P messaging platform for enterprises, resellers & mobile operators with global network coverage.