So what does PBX mean? PBX is short for Private Branch Exchange and a PBX is an office phone system, within a company. With a PBX you can call both within the company and externally to customers and partners.
Traditional PBX systems handled telephony over the fixed landline, with the hardware of the PBX situated at the company’s premises. Copper telephony landlines connected to a PBX box.
IP PBX uses the internet to carry the calls, instead of analog landlines. IP PBX systems are often hosted, which means that the system is managed by a service provider. Then you will have your ZIP-trunk on the service providers premise.
Cloud PBX systems, often called virtual office phone systems, are completely cloud based. Companies that uses this type of technology do not need to invest in any hardware to carry the PBX. This is completely maintained by the provider. With cloud PBX you only need the headsets, computers and phones you wish to use to make the calls.