I was just wondering if offline jumpseaters are required to list ahead of time to ride as an OMC with a seat in the back on United on international flights. If so, who do I call?

I've done it a hand full of times it the past with no issue without listing. Ive always been told offline pilots cant list for the jumpseat. However, a couple days ago I travelled from ORD to HKG and had some issues. I checked in at the gate about 90 minutes prior as soon as an agent showed up. They took my info and I
thought all was good. However, when I went to check 15 minutes prior to departure if they assigned me a seat the two agents told me that they can't just give me a seat for an intl flight and that they needed my passport info 24 hours prior. It took a little polite pleading to convince them that I can't list ahead of time and that it's never been an issue in the past before they gave me a seat.

With that being said, once I got on the CA and his crew were absolutely awesome. The CA came downstairs personally to introduce me to the lead FA whom I had already met and to check if there were any better seats available. By some miracle there were two Business Class seats available and the CA made sure I was sitting in one. The lead FA and the crew were great the entire flight. It made a 16 hour flight much more pleasurable. Huge thanks to that crew.

So back to the original question. I want to ride back from HKG to ORD as an OMC. Do I need to list ahead of time?

Thanks for the info.