findContact("123");
findContact("1234");
findContact("12345");
findContact("123456");
findContact("1234567");
findContact("12345678");
...

private void findContact(String number){
    Uri uri = Uri.withAppendedPath(PhoneLookup.CONTENT_FILTER_URI, Uri.encode(number));
    ContentResolver cr = getContentResolver();
    Cursor phoneCursor = cr.query(uri, null, null, null, null);
    while(phoneCursor.moveToNext()){
        Log.e(TAG, number + "t" +phoneCursor.getString(phoneCursor.getColumnIndex(PhoneLookup._ID)));
    }

    phoneCursor.close();
}