Unmask Private Numbers

[Samurai Legend]

I was doing research on how to unmask private numbers and I only came across one article where someone stated you can do it using Raspberry Pi 

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If you have the skills to build miniature electronics circuits, and know how to use things like raspberry PI’s and/or Arduino's, then you can connect your phone line to a suitable circuit, that then feeds the signalling direct from the phone line into the device for decoding.

In the UK, caller line ID is sent as a series of network control tones on the signalling circuits, while the phone is actively ringing (In most cases this signalling is handled using SS7 or similar)

When a number is withheld, the caller ID data IS STILL PRESENT within that signalling data, but it has a flag set on it that tells the receiver being signalled NOT TO DISPLAY IT.

It’s perfectly possible to build an electronics circuit that can read this signalling data, ignore the flag, and display the number anyway.

Even if the sending network does not provide said flag, the network will still generate the data here in the UK, because it’s part of the rules, that ALL telecoms network operators here in the UK have to provide it.

My problem here is I have no idea on where to start and I am receiving calls on my mobile phone and not on a landline. However, I was thinking if I can't connect my phone to the Raspberry Pi. I'll just redirect the call to a landline where the Raspberry Pi can log the details.

If anyone has information on how to do what I require. I will reward you.