Cloud providers need to be able to bring everything to the table in order to compete and win.  In today's landscape, the best value a service provider can bring is consolidating all technology onto one invoice.  Fax to email is one of the easiest up-sells you can introduce.  Fax usage has surprisingly not gone anywhere.  Most likely due to the industries that still require it for compliance such as HIPPA and accounting.  That is why offering a compliant solution under your own brand and billing with a per page model may be the MRR "mix-up" you've been looking for.