On Nokia S60 (like Nokia 6680) and Nokia Series 80 (like Nokia 9300i), you have to catch an Error (not Exception; better catch Throwable) when you call
This is thrown (Symbian OS -2 on Nokia 6680 and -36 on Nokia 9300i) when you are in the Offline profile or on Nokia Series 80 when GSM tranceiver is turned off (through turning off the Nokia Series 40 part). This issue is quite handy, actually, as it tells you whether the GSM radio is turned off.

Furthermore, there will be no message dialog when you have an uncaught Error. The MIDlet just quits, so catch this Error in your code. Makes it difficult to debug.