In this case, the PBX software is installed on an external server and only accessible via internet. Depending on the provider, you have different access and configuration rights. The pricing models usually are user-based and differ greatly. Also, the cloud PBX provider usually takes care of the maintenance, and in many cases a particular SIP trunk is predetermined. The main advantage is the central location of the IP PBX. IP phones can be registered to the PBX independent of their location. This way, employees in home offices or in branch offices around the world, can be easily integrated.
The initial costs for hosted PBX are often lower as less own hardware is required on site, and the costs are incurred on a monthly base. However, this may become more expensive in the long term. Hosted solutions also provide less control as the PBX is located outside the company and internet service providers (ISPs) often can not be freely selected. In addition, even internal calls between employees are routed through the Internet, and therefore require a fast internet connection.