I wouldn’t sit and talk so much on the phone but really, just making shabbos plans and llving day to day life – needing to be in touch and arrange stuff with people, you use minutes.
Also, when looking at your daughter’s bill (especially for people who do minute by minute), remember that you start off with a whole bunch of fees to begin with-the cell rental, the emergency txt thing, etc. -the bill is starting off with around $15 at best and then she uses minutes-what do you expect it to be? Don’t expect it to be an unreasonable amout on the bill.
My guess is at least 300 or 400 minutes. Just MHO.