Intercepting the Native Phone Calls

That sounds like a total violation of privacy unless you are talking about your own phone conversations on your own phone. It might even be illegal in some countries.

We do respect privacy of every user and we are trying to make our solution GDPR compliant. Because we are trying to protect customers from getting scammed by the calls.

There is a much better solution to prevent scams:

Get Your iPhone to Ask Callers Who They Are Before You Answer

https://www.macrumors.com/how-to/get-iphone-ask-callers-before-answer/

And this is compliant with any country regulation.

is it customisable with third party apps ?

is it customisable with third party apps ?

I don't think so, this is a system function.

What type of customisation would you need ?

You could file a Feedback asking for improvement and capability to change some settings.

I am trying to develop a solution to intercept a native cellular phone call, process its conversation audio or screen call before it is been answered. Do we have any framework to build such kind of feature.

No, nothing like this exists. CallKit manages how audio session control is moved between clients (including Phone.app) but the audio session itself is still owned and controlled by the app itself. That means the app that controls a given call is the only component that has access to that calls audio.

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Kevin Elliott
DTS Engineer, CoreOS/Hardware