RingCentral - RingCentral is the leading provider of cloud-based communications and collaboration solutions for small business and enterprise companies
InStream CRM - Business relationship management platform - CRM alternative
Dialpad - Switch is a cloud-based phone system built for Google Apps users.
Onesheet CRM - The Simple CRM for Google Sheets
Aircall - Aircall is a call center software of a new generation designed for fast growing companies. Setup instantly and integrates to your CRMs
Crmble - Easy peasy crm for Trello