Call recorder without server

Question

I searched the web, and found that there is no call recorder which records calls directly, all the apps call through server and store and play.

Is there any clue, such that a call recorder without server can be made, which can record call when we call directly from our phone and not from any app.

Answer 1

(Posted an answer, paraphrased from a comment ) .

Apple would not accept this type of app, since you need to work with a jail-broken device.