olemus
virtuaalkeskjaam,
marsruutimise eest hoolitseb VoIP-teenuse andja
=
virtual PBX as a cloud telephone service

ülevaateid
http://www.voip-info.org/wiki/view/Cloud+PBX

https://telzio.com/blog/what-is-a-cloud-pbx

https://www.avoxi.com/blog/what-is-a-cloud-pbx/