Interesting article
So voice calls are (badly) handled with an outdated model for accounting purposes.
In Luxembourg (where I work), I have a company phone with a 15GB data plan. Any call to any Luxembourg number is free. I have the option of declaring a favorite country (fyi : in Luxembourg, border workers are ten times the amount of national workers). Obviously, living in France, I declared that as my favorite country. Calls made to French numbers are thus free as well. I do pay a small amount for international SMS.
Basically, the only thing I see making money for my telco is the monthly allowance (and, at €40, it's not so much compared to what I've seen elsewhere), and the international calls I have to make from time to time (other than France). Oh, and premium numbers, obviously.
Seems it is possible for a telco to make a living without scrounging every last cent from its customers after all.