I have a question. Seeing as a business pbx client must also have a phone number from the reseller in order to forward the number to an extension in the pbx, wouldn't it be advantagous for the reseller to be able to have the option to enable a pbx in the clients phone number control panel?

This will be better for the client, as the client will only have to log into one control panel rather than two (phone number and pbx control panels)