Old school business phone systems ran through a physical PBX (Private Branch eXchange) box inside an office location. VoIP Phone System (Hosted PBX) is the cloud-based virtual version of that same technology delivered over an Internet connection.
'Hosted PBX’ is a telco term. Out in the real world, it’s called by many names such as business voice, business VoIP, business voice over Internet, broadband phone service, etc. Essentially, all those terms relate to the same underlying technology – which is Hosted PBX. It boasts more than 40 advanced features such as auto attendant, conferencing, hunt groups, and music-on-hold.