CometChat - Seamless Real-Time Chat Integration for Your Applications.
Twilio - Brings voice and messaging to your web and mobile applications.
HappyFox Chat - HappyFox Chat is a live chat software for the websites.
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
Taskworld - Taskworld is a cloud-based collaboration platform that increases productivity, engagement at work.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates