My cell phone is recording all phone calls (using Automatical Call Recorder on Android) and this has helped me a lot of times (both because I didn't hear something very clearly or as evidence for something).
Now I want to do the same for my landline phone (RJ11 connection, Belgian phone line). I have a Raspberry Pi 3 Mode B I received as a gift and haven't used yet. I was wondering if I could use my Raspberry Pi for this? In the ideal scenario it's recording all calls and storing them on my NAS.
I'm a programmer so if necessary I can code. I have little to none experience with building electronics.
Is this doable? If yes, where/how do I start?