The third party billing has been going on for years, they love getting restaurants with it. this is how it works as told to me by a verzion employee who frequents my restaurant.
they call you asking if this is Mr. XYZ? or to make sure the number is business listed as XYZ Business, once you say "yes" to "confirm" they are allowed to add any services and charges to your bill, from basic small charges to service charges for monthy options you never "techinally" agreed to.
The larger your company is and the higher the bill the more "services" they will add to your bill, because they will probably slip past you. where the basic person would notice, a $15 increase, they will add small charges like $1 or 2 at a time every few months, and before you know it your paying thru the nose.
My dad still has a land line for his business and checks his bill every month as he was getting charged for all sorts of things he didnt sign up for.
you can usually get the charges reversed or at least dropped my calling customer service and asking for the person in charge, skip the out sourced tech people and go to the higher ups.
They credited my dads bill and removed all charges.
We now have magic jack for just $1.70 a month
, but really we do, works great for the basic calls.