Re: Said like someone that doesn't work in telecoms
So no hunt groups, pick up groups, voicemail, synchronizing with exchange, presence, follow-me, least cost routing, permissions, time based routing, IVR,redundancy, multi-tenancy, call recording, auditing, multi-lines appreance, barge-in, PA routing, faxing, emergency routing, vpn's...
All of which, and more, were being done by the main exchanges long before they became economical enough to be added to PABXs.
Sure, if you have a private planet-wide phone network you may want that stuff in-house, although since the article suggests outsourcing them to "the cloud" you might as well call the BT network the "phone cloud" and outsource it back to them.
(oh, and I've worked in telecomms 30+ years, on both customer and supplier sides)