How to hide your phone number

Hi,

From a mobile phone,
#31# before a number works but only from a mobile. (*31# to activate number withholding)

For a landline (traditional line through France Telecom),
3651 followed by the number works well

For unbundled phones, I suppose it depends on your provider!
Free (my provider) has a difference between hiding your number for one call or for all calls:
*31# to activate the "hide number" function
#31# to deactivate it
*#31# to find out the status?
to make a call, prefix it with (before the number)
3651 activates the service during a call (so hiding your number)
3652 deactivates the service (thus transmitting your number)

Good luck!