#746025625# ,when dialed,tells whether the SIM CLOCK STOP ALLOWED or similar, depending on your SIM card.
Newer SIMs have a feature called 'clock stopping' that allows the phone to save energy -- it is a kind of sleep mode for SIM cards.
Not all versions of software support this.
You cannot turn the SIM clock on and off, the phone will do it automatically if the SIM supports clock stopping.
