#define MM_KEY_UP (73)
#define MM_KEY_DOWN (74)

....
// This connects application to D-Bus event from zoom keys

QDBusConnection::systemBus().connect(QString(), QString(),                 "com.nokia.tklock.signal", "mm_key_press", this, SLOT(_zoom_keys_handler(quint32,quint32)));

....

void DBusClient::_zoom_keys_handler(quint32 code, quint32 /*ignored*/) {
	emit zoomKeyPressed(code);
}

...

if (code == MM_KEY_DOWN) {
    if (behavior == "track") {
        _player_form->next();
        _dbus_client.setVolume(_system_volume);
    }
} else if (code == MM_KEY_UP) {
    if (behavior == "track") {
        _player_form->prev();
        _dbus_client.setVolume(_system_volume);
    }
}

_unpause_keys_message = QDBusMessage::createMethodCall("com.nokia.mce", "/com/nokia/mce/request", "com.nokia.mce.request", "req_keypad_off_pause");

....

void DBusClient::_unpause_keys() {
	QDBusConnection::systemBus().call(_unpause_keys_message);
}