How to turn on the speaker during a call

I am trying to turn on the loudspeaker during a call. I have tried this code. Register a new listener. But it doesn't work. It shows a toast message, but the speaker is still silent (only speaker is used by default).

@Override
    public void onCallStateChanged(int state, String incomingNumber) {
        super.onCallStateChanged(state, incomingNumber);
        switch (state) {
            case TelephonyManager.CALL_STATE_OFFHOOK:
                Log.i(LOG_TAG, "onCallStateChanged: CALL_STATE_OFFHOOK");
                try {
                    Thread.sleep(10000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                Toast.makeText(mContext,"Call, time to turn speaker on",Toast.LENGTH_SHORT).show();
                AudioManager audioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
                audioManager.setSpeakerphoneOn(true);
                break;
        }
    }

      

        
        
        
      

    

Of course I added permissions to my AndroidManifest.xml.

<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />

      

        
        
        
      

    

EDIT

This doesn't work either. It returns false (message Toast false);

case TelephonyManager.CALL_STATE_OFFHOOK:
                Log.i(LOG_TAG, "onCallStateChanged: CALL_STATE_OFFHOOK");
                try {

                    Thread.sleep(10000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                     Toast.makeText(mContext,"Call, time to turn speaker on",Toast.LENGTH_SHORT).show();
                audioManager = (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);
                ((Activity)mContext).setVolumeControlStream(AudioManager.STREAM_VOICE_CALL);
                audioManager.setMode(AudioManager.MODE_IN_CALL);
                audioManager.setSpeakerphoneOn(true);
                boolean check = audioManager.isSpeakerphoneOn();
                Toast.makeText(mContext, "Speaker is on :" +String.valueOf(check),Toast.LENGTH_SHORT).show();
                break;