RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
PagerDuty - Cloud based monitoring service
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
OpsGenie - Alerting and On-Call Management for Dev&Ops Teams
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.