Siemens S1 Secrets (also work on other models)

Show IMEI
*#06#
Tetris
Power on phone and enter PIN. before phone has locked onto network, F9, send own number, hit right button, hit 9. left is 2, right is 8, rotate is 5,
and drop is 4.
Monitor Mode
Menu, 9 (Phone Options), 7 (Phone Status), Left Display Button (left MENU key), 5553756, HangUp Button (Red HandSet key)
Now “Monitor” should appear at the bottom of the Network Options menu.
Pressing the right Display Button when in monitor mode will show a list of the
six cells with the strongest signals.