In essence, there are three types of VoIP Service: In-house, hosted and hybrid.
Inhouse VoIP Systems. These can be found in the very large down to the small business.
Hosted VoIP systems.
Hybrid systems.
What is VoIP and do I need it?
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A VoIP system converts analog voice signals into digital signals over your broadband connection. A VoIP server is used to connect calls to other telephone networks. As long as you have a high-speed internet connection, which includes a router and modem, you are ready to use a VoIP.