Works on Android 9.0 (Android P) has already started, with the first developer preview getting set to be completed. The Andriod P will come with a new native support for call recording both on the callers and receivers ends, so the use of third-party recording apps will totally be eliminated. I think this is an interesting feature.
The Android Open Source Project (AOSP) has been fed with some new codes which hints at the existence of a “call recording tone” that is expected to be played when a user presses the corresponding button in order to start recording their conversation.
The tone is reportedly of the 1,400Hz variety which will allow both the young and old hear it without straining their ears. According to a commit, it is meant to be played every 15 seconds while the conversation is being recorded, likely to remind the person who didn’t initiate the recording that it’s still participating in one.
While just less than 1% of devices are running Android 8.0 Oreo, Android 9 is already warming up.