How to hide, or vice versa, not hide your number for a specific contact list?

Question

Android

There is a Google Nexus S with Android 2.3.4, there is a subscription to anti-AON from Kyivstar. In the settings, I can specify hiding the number, but the number will always be hidden. And how can I make the number hidden from everyone except a certain list of contacts / numbers? Or, in extreme cases, it was possible to decide before the call whether to hide the number or not?
The number is supposedly taken from the contact list, so all sorts of #31# will not work, too lazy to edit the numbers, I want a more direct solution.

Answer 1

Figured it out myself. A group of contacts is being made, I created Trusted, and put all the contacts for which I do not want to hide the number there, and in the phone settings I set the hiding for everyone.
The Prefixer application is installed, the rule is configured: add the *31# prefix to the numbers of the Trusted group.
The application will automatically add the number opening code when calling the Trusted group, and everyone else will not see the number due to the default policy.

Answer 2

it all depends on the operator, it is he who controls it. it's just that for some you can change this option yourself through the phone settings

Answer 3

Not all

Answer 4

I can not make it show my number there "unknown" I press and does not react in any way. Tell me something