Having data enabled for your car ( a.k.a. "the hotspot" ) does not provide you with only WiFi "in flight" ... it gives you access to your side of the remote control for the vehicle - start car remote, lock vehicle, track vehicle, etc. Even if you put a hotspot in the car, turned ON at all times ( say ... TMO, or Verizon ), it won't give you access to those features. It has to be the "native" one.
For the vehicles that have PIVI, no carrier in US will "see" them on their system. The IMEI and the ICCID embedded in the vehicle, belongs to TATA COMMUNICATIONS, which is located in Netherlands. Yes, it is crazy, but ...
ALL the LRs that are on PIVI ( not InControl ) are on a TATA MOTORS M.V.N.O. in US.
They buy buckets of data from ATT, and then "re-sell" it to your car, or mine, or any one else on PIVI in the USA.
If you have the service, and hardware, the dealer can do a "shared secrets" and restart your data.
Anyways, I had this issue on my Defender in the beginning, and the dealer was super nice and fixed this issue in one visit !

 

Thanks all for the help. I also want to know how to enable a mobile hotspot and that is why I am searching for it online and I am glad I found your post. When I was searching for it online, I also found https://writinguniverse.com/essay-types/ website where I found a lot of essay types. Now, I can easily choose the topic to write my essay assignments because I always face problems in choosing the best essay topic.