You might be able to hack the card, but it won't help for several reasons.
Whether using data or call functionality, the "antennas" of the cell companies (which could sometimes be a shutfus from several providers) need to ID you, and get approval, ie, is your card member of the network, is the card line active (or. suspended for not paying a bill) or active balance for prepay, and in roaming, whether the original operator allows this line to work (or not, eg blocked for roaming).
Every sim card has a phone number eg 972 540 235623, but also a sim serial, which looks like 806523652146/963, and is just like the phone number unique.
When activating a new number by an operator, they know that this sim belongs to them, and gets activated, however, if the number isn't one of them, it is requested via a central point, who in return check with the operator where the number is currently held, and they decide whether to release or not (this part is strictly governed by law).
They release it to the central point, who then in turn hands it over to the operator.
This means that a certain sim number can only be active by one operator at the time.
If you copy the sim phone number and serial of someone else, you can speak on his account.
The last one turning on his phone, will get the network to himself (very few operators allow more then one working at the time; you could test it by activating a dual sim).
Data might work for both simultaneously.
