olemus
VoIP-side kodukeskjaam, aparatuurina või tarkvarana
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a system that connects telephone extensions to the public switched telephone network (PSTN) and provides internal communication with IP connectivity

ülevaateid
https://xenexsystems.com.au/blog/what-are-the-different-types-of-pbx-systems/

https://www.voip-info.org/ip-pbx-architecture/

https://en.wikipedia.org/wiki/IP_PBX

näiteid
https://www.trustradius.com/ip-pbx

https://hodusoft.com/top-10-ip-pbx-software-for-2021/