I have a Nokia 6230i with software version 3.62 and when I try to add a new contact to the phonebook (with only the SIM memory selected), the phones says "Operation failed"! But when I turn off the phone and then I turn it on, the new contact appears in the SIM! Can anyone (maybe with the same software version) confirm this?

Then, I discovered (because I own several SIMs), that the phone stores some messages when they arrive not in the SIM but in an unknown memory area of the phone! I mean, I receive a message with a SIM, and when I change the SIM the message is there, stored somewhere in the phone!
I discovered that this happens also with Nokia 8310 and 6310i!

About Nokia 6230i, I also discovered, using PC Suite, when I go in the inbox, that in the phone were stored messages I erased some time before (and that you can't see from inbox in the phone)!
I deleted one of them, PC Suite put it in the recycle bin, and when I selected inbox again, those messages were all disappeared!