Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Maytapi - Serverless Whatsapp Api with Chat and Agent support.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Octopush - Octopush is a company providing technology-based communication solutions, including SMS, Web solutions, and Email APIs.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
CheapGlobalSMS - Send instant bulk SMS worldwide, with reliable SMS delivery and reports in real-time.