Twilio - Brings voice and messaging to your web and mobile applications.
Birdeye - #1 most trusted reputation and customer experience platform for local business
Bandwidth - Bandwidth offers SIP trunking, Emergency communications, and Voice & Messaging APIs.
Reputation.com - Reputation.com is a solution for tracking and improving online reviews, social media, and local search visibility for businesses.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Podium - Podium helps your business get more customer reviews, manage customer feedback, customer interaction, and online review management from one software.