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.
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
Infobip - A2P messaging platform for enterprises, resellers & mobile operators with global network coverage.
CONTUS MirrorFly - World's Most Scalable Chat APIs & SDKs for Small, Medium & Enterprises
Textlocal - Textlocal is an app that allows for individual and group texting. It is designed for businesses that have employers and employees who need to communicate with each other, making it easier to announce group meetings and special announcements.