if anyone is wondering. the Telcel sim card with data does work in the USA. We loaded 4 gb before we left Mexico. Currently in Pennsylvania and it is working great. Worked in Texas, Louisiana, Mississ...
If you are paying money to Telcel, you do have Telcel plan, even if prepaid.
With Telcel prepaid one can get away for as little as 150 pesos a year if it's not used often. After balance has expired, you can't initiate the call but the number remains active for incoming calls for another few months.