How to set "privacy full" in one particular extension

Hi, I’ve been working with an Asterisk and I need to set that all call originated by an specific extension the ANI (CgPN) is not shown in the remote telephone. All calls from other extensions should be shown.
For this, according to RFC 3398, the outgoing INVITE should send in the FROM field “privacy=full”, and the current ANI.
ANI is needed because if the call goes to a mobile phone, the mobile company needs ANI to charge CPP. That’s why I cannot send “anonymous”.
I’ve been trying to configure this in the config files, but nothing seems to set this.
Please if any one has a way to configure this, I would appreciatte.