VoIP is known as Voice Over Internet Protocol, a technology that allows you to make phone calls using the Internet. A PBX is Private Branch Exchange (PBX), a telecommunications system that interconnects telephone switches to a local area network (LAN) or other similar systems. PBX is a private system that allows an organization to control telephones centrally, for example, to provide numerous telephone extensions, line appearances, routes, and hunt groups. Aavaz best free VoIP PBX is a telephone system. It provides call forwarding, recording, voice mail, making calls from a virtual extension, etc. Like a regular PBX, it's installed in the office and connects to all the phones.