Below is a breakdown of the different models
VoIP PBXs are business phone systems that typically reside at the customer premise in a phone or data closet. These systems converge your voice traffic onto your existing data network. This convergence allows people to use different forms of communication, different devices, and different media to communicate to anyone, anywhere and at any time. Systems frequently allow for integration of other business systems including but not limited to real-time communication services such as instant messaging (chat), presence information, business CRMs, voicemail to email, video conferencing, fax to email, and mobility.
This is a hosted PBX system that delivers PBX functionality as a service, available over the Public Switched Telephone Network (PSTN) and/or the Internet. Hosted PBXs are typically provided by the telephone company, using equipment located in the premises of the service provider’s exchange.
This means the business doesn’t need to buy or install PBX equipment (generally the service is provided by a lease agreement). The telephone company can, in some configurations, use the same switching equipment to service multiple PBX hosting accounts. Instead of buying PBX equipment, users contract for PBX services from a hosted PBX service provider, a type of application service provider (ASP), which is a common source for computer-based services delivered over a network.
This is the licensing of VoIP systems, Internet access, telephone access, and more. It is similar to an ASP model, where you purchase and pay for what you need and the provider houses, maintains, and owns the required equipment. In this model the business phone system is housed in the provider’s central office, and they provide the data network components, the phones, and voice services.