Originally Posted by
MSPeconomist
When I first did it, I had the impression that it was an unpublished DM benefit, but I've since learned that it's not restricted to elites. I'm pretty sure that I've done it by phone at least once, although I've also had phone agents tell me that I must clear customs before trying.
I usually tweet DeltaAssist right after my intl. flight lands, and they usually put the segment in the reservation to hold the space. Then I go through customs, and get the ticket reissued at the service desk.