You didn't give details here, but you are not allowed to ride jumpseat on international flights on most carriers (Atlas, and a few other cargo guys will allow it except for FE and UPS). This is not personal on the parts of these carriers. TSA has restricted CASS as domestic only. And while I-CASS does exist in theory, it is still not in use today. So don't hold it against your fellow pilots at mainline for not allowing you an international jumpseat.