olemus
virtuaalkeskjaam, mille 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/