Detecting new MMS (Android 2.1)

Question

I'd like to recognize arrival of new MMS msg (after it is downloaded to inbox). I am doing the following:

private MMSContentObserver mMmsCO;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    h = new Handler();
    mMmsCO = new MMSContentObserver(h);
    getContentResolver().registerContentObserver (Uri.parse("content://mms"), true, mMmsCO);
}

where

    private class MMSContentObserver extends ContentObserver {

    public MMSContentObserver(Handler h) {
        super(h);
    }               

    @Override
    public boolean deliverSelfNotifications() {
        return false;
    }

    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);
    }
}

However, onChange is not getting called. What am I missing? Thanks in advance.