PNLM list overwritten

Hil list Today I've observed a strange behaviour when modifying the PNLM of some real networks expired sims (to be used with osmocom and openbts). I've put 001 01 on the top of the list. I've ejected and reinsterted the sim in the reader many times, and I'm sure that the value has been wrtitten. When trying to connect to my test operator I get the message "your sim card doesn't allow the connection to this network operator" from my android phone. Reading again the pnlm I see that the original list has been restored. This astonishes me... Is is possible that the SIM overwrites the list by itselt? Or is it the phone that does it? The android has an original, not branded, operating system. Thanks everybody for your help. Dario