For two days in a row, I keep on getting SIM card error on my Sony Ericsson M600i. The phone is only several months old (almost four months); the SIM card is five years old (since this is a Smart line).

Actually, there was already a problem when I first inserted the Smart SIM card after I got this phone. When I first powered it up, the phone cried out “No SIM card”. I had to reinsert and power on the phone several times. To check if the phone was defective, I inserted my Sun SIM; in one snap, the phone worked. So it was not the phone. After reinserting the Smart SIM several times, the phone worked.

I got the occassional SIM card error when the phone is shaken (i.e., fell from the bed). Now, just a little shake, and I get the error. So last night, I inserted the Sun SIM (purchased less than 6 months ago), and the phone worked.

Now: is it the phone or the SIM card?

(Will Smart replace the SIM card while retaining the same number assigned to me?)