A while ago I was helping a friend pick a cell phone plan with T-Mobile USA. If you study their plans, the "Essentials" plan does not include "taxes and fees", but their "Magenta" plan does. When contacting T-Mobile, they could not tell me what the fees were even after providing the specific ZIP code. They said I would have to sign up for the plan first, and could then see the fees on the bill. Even when I told them that the choice of plan would depend on the amount of taxes and fees, they were not able to tell me and said that I could look at the current cell phone bill with the current carrier, and that the taxes and fees should be similar.
It is crazy they can't tell you how much you'll be paying before signing up.
It is crazy they can't tell you how much you'll be paying before signing up.