Now here's his variant of the story: The SIM is like a fuse for the antenna, so if there are some frequency fluctuations the SIM card is the first one that gets fried just to protect the GSM Driver (chips or whatever). He told me that once a customer came with a FRIED (but the good kind of frying, that the SIM was physically burnt, with visible marks of burning) SIM card, they replaced the SIM and the phone worked beautifully for 2 more years flawlessly until the customer came to get a new phone.