Use InCallService methods without replacing the default phone app

Question

I'm developing an Android app that enables the loudspeaker during a call.

Starting from Android 10 the AudioManager#setSpeakerphoneOn(boolean) is not working anymore and developers are encouraged to use the InCallService#setAudioRoute(int).

My question is, how can I use (if possible) InCallService's methods without replacing the default dialer (and implement a lot of stuff I would not use...)?

Thanks