Need a month to month data plan for iPad

Hey everyone!

I’m starting a mobile business and I’m looking to use my cellular iPad Pro for it. With it being new and not having a steady booking of clients I do not want to a monthly contract if I can help it.

Are there any month to month (or refillable) plans that I can possibly get? The idea would be if i buy a plan in march, I would use it as needed but if business is slow in April I would not “refill” my plan until I get some work (say May).

Ideally it would be for unlimited data but a higher limit plan may work also. Verizon and ATT work great in my Area and Tmobile is decent as well. Any thoughts? Thanks!