Unblocking witheheld numbers

I’m trying to set up a method of unblockinig withheld numbers.

I understand I need a SIP provider that supplies the ANI and was wondering if anyone knew which providers do this?

Also if anyone could give me general advice with regards how to unblock withheld numbers (in the UK) it would be much appreciated.

In the UK, you need to be an official network operator, or the emergency services. My feeling is that you would already know the answer if you were.

Network operators are trusted not to misuse blocked numbers, i.e. only to make use of them in their network operator role, not for any other service they might provide.

That’s what I always thought but if I recieve a call from a withheld number and then forward it to a DID, I understand my SIP provider can be configured to remove the privacy flag. Is this not so?

If you are trying to replace, rather than unblock, a withheld number, have a look at the ${CALLERPRES} function.