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
Plivo - Plivo simplifies your customer engagement.
BulkSMS - SMS messaging service provider offering two-way SMS communication services.
Applozic - Chat API & In-App Messaging SDK for Mobile & Web Apps Innovate fast, save development cost and delight users with a scalable, secure and customizable Chat
Digimiles - Digimiles is A2P messaging platform that enables startups, SMEs, businesses and corporate's to market their products and interact with their customers 24/7 effectively.