hlw there can u plz help me



we have sim cards which are on site sending an Sms if there is a fault. The problem we have is that the sim cards are being stolen and those who steal them use them on there phones
i was hoping if you can tell me how to fix a sim card to only work on our modems only and not on the phone like if you remove the sim card from the modems(field modems) it does not work not even on a portable modem