If you're trying to save data on the SIM card itself - contacts, call/message history, personal files, whatever - then you'll find many phones do things differently.
Some automatically store (private) junk on SIM cards whether you want it there or not.
Some refuse to write anything to SIM card nvflash. Some of these make the contents of the SIM card invisible/unreadable to end-users, some provide file managers which will let you view (and perhaps save or delete) certain user files.
I wouldn't advise using SIM cards as data storage devices. Different devices access SIM card storage areas in different ways, the cards are unreliable for transferring data between devices. Reduced capacity (or extra bloat) on the cards can impair normal operation on some devices. And their low-cost low-density capacity is puny anyhow.
An SD card is a far better choice for storing files. A cloud account is a far better choice for (re)storing contacts and communication logs.
