3CX Cloud Server is a separate edition of 3CX Phone System that allows you to host up to 50 separate 3CX Phone System instances on one Windows Server machine. Each instance is entirely separate from the other. Because it runs on Windows Server 2012 and uses 3CX Phone System, you can leverage your existing windows knowledge without having to learn a new operating system or complex software platform to offer a hosted / virtual PBX.
Connect each instance to its own dedicated SIP trunk or Gateway port and keep call billing perfectly separated for each customer. As a reseller, maintain close customer contact for PBX services, but outsource telecom call costs and billing to your SIP trunk provider of choice. As a SIP trunk provider, keep enjoying economies of scale by keeping control of the SIP trunks, but outsource PBX support and service to your resellers – allowing you to scale easily.