Virtual PBX systems, cloud PBX systems or hosted PBX systems are business telephone systems that deliver PBX functionality as a service, available over the public switched telephone network (PSTN) or the Internet. Hosted PBXs are typically provided by a telephone company or service provider, using equipment located in the premises of a telephone exchange or the provider's data center. This means the customer does not need to buy or install PBX equipment. Generally the service is provided by a lease agreement and the provider can, in some configurations, use the same switching equipment to service multiple hosted PBX customers.
See Melrose Labs Voice Gateway/CloudPBX
Melrose Labs: Our mission is to deliver pivotal services in cloud communications across mobile, fixed-line and internet for enterprises of all sizes. These services allow organisations to improve their effectiveness, increase revenues and reduce costs when they use our cutting-edge communication services in business operations, and with customers and staff.