Cheaper to just "Host" the system onsite at the customers location and charge them the monthly fee for everything included. Otherwise it's a Synnex or Avaya Live types that get the hosted piece of the pie.
The word "Hosted" or "Cloud" kinda takes the small business partner out of the equation, and they either become a reseller of hosted company A or company B, with a small margin.
For now, hosted companies have really screwed over the customer by poor service, poor quality, and undelivered promises, but once everyone has GigaGoogleGoGoGadgetFiber links to the internet with managed services right on the link in 10 or 20 years who knows where we will be? The traditional method of onsite phone equipment may go away.