Military people in this line of work, where life and death is all around you, sort of develop a 'gallows humor' attitude. Weird and sick jokes abound and it helps to deal with the tension.

The "Hotline" between the Pentagon and the Kremlin used to be a Tele-type machine and it was tested every hour; one hour by us and the alternate hour by them. The insults and dirty jokes used to test the system helped to break up the tension as both sides tried to outdo the other.

When information was picked up about a death in a family the other side would send a message of condolence.

I would bet that after awhile the US piliots and the Iranian ATC's get to know each others voice. In this case it looks to me like both sides had to do what they had to do with the notification stuff, but neither wanted to get somebody killed just because the pilot might have been taking a little shortcut.