How to turn speaker on during call

I am trying to turn speaker on while making a call. I have tried this code. Register new phone listener. But this doesn't work. It shows toast message, but speaker is still silent (only earpiece 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 permisions in my AndroidManifest.xml.

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