RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
ShoreTel - Cloud phone system & contact center software & services
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
CorvisaOne - CorvisaOne is another cloud-based communications suite that is specially designed for companies that need features for managing inbound or outbound call centres.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
NICE inContact - Get the DMG Consulting report reprint on cloud contact centers.