I was on the phone with a res agent last night when I was booking an all UA metal flight on ua.com. After confirming all my flights having I inventories available, I asked him to stay on the line with me while I clicked the "purchase" button on ua.com so that I can have him to upgrade all my flights right the way. As I was waiting for the confirm screen to come up, he told me that he can see the itinerary from his end already.