The best call recording apps [UK]

[Noobtechninja]

Hi there guys.

I could really do with some help here.

Situation:
The sister, of a very good friend of mine is experiencing abusive phone calls from her ex.
He is extremely degrading & aggressive, he plays mind games & gasllights her
(he also does this when on the call with his children).

We need to keep a record of these calls/conversations, as if anyone pulls him up about
his behavior he is incredibly convincing, and portrays himself as the pinnacle of a
reasonable and well intentioned man.


Questions:

1. Which apps are the best for recording phone calls in the UK

2. That allow recording of both parties of the call

3. That (do not) beep or alert the other person that the call is being recorded.

(We're happy to sideload apps if needs be).


Handset type:
I believe that the sister is using a Samsung J7, on Android 9
(However I am waiting for this to be confirmed)

TIA for any help and advice, I apologise (for, perhaps TMI) but I think its helpful
to understand the background of the situation, to help us out.

Thank you very much.