YouMail - YouMail turns visual voicemail into a personal assistant for handling all your missed calls.
RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
Hi Voicemail - Stop robocallers filling up your voicemail
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
MightyCall - Virtual phone system that lets you run your business from anywhere.
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs