I am an Intermedia Reseller and I can't stand their system. Plus as a partner, the end user cannot call Intermedia for support. This is no fun.
Are you looking for a reseller/partner solution? Then I would look at 3CX They have the business model.
Yes. I want to interact with the end user for config of features only (OS and app maintenance handled by anyone other than me) and I want revenue from the sale of hardware and setup, and I want recurring revenue from monthly fees. The recurring revenue must be charged to me so I can bill the customer at my rates.