Don't switch off, as deprives the real callers to find you offline should there be any..

Type this....*21*122# and press the green/send and you will be forwarded to either the voicemail (voda) or txt box qtel (by default)

For the caller he finds you power off, your requirement achieved.

For you/receiver, you will get txt message/s stating the mobile number of the caller instantly...

Then it is your will to return the call immediately to the real family/friend and ignore others...plus the stream of txt messages will be helpful in case you are forced to register a police complain

Now to return your phone to normal state dial #21# and press send. (Btw: This is applicable for both QTEL & Voda)

Hope this helps..