Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Smart Communications - Smart Communications enables companies to create, manage and deliver personalized communications to its customers and partners.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
NextPlane - NextPlane offers cloud-based, scalable unified communications federation service for the enterprise.
Plivo - Plivo simplifies your customer engagement.
Voxer - Turn your phone into a Walkie Talkie. Don't waste time on phone calls and voicemails.