EasyCall Phone Call Center - Instantly provide voice customer support through phone calls.
BVoIP - BVoIP allows to easily add Cloud & On-Premise VoIP PBX to the product offering without having to re-invent the wheel or add another layer to the daily operations..
CallKite - Your website’s video call center in just one click.
GoTo Connect - Jive PBX is a communication solution that offers remote communication services to companies such as video conferencing, text, and chat services.
Daily.co for Intercom - Free video calls & screen shares embedded in Intercom
Dialpad - Switch is a cloud-based phone system built for Google Apps users.