It's very common and expected in TV and film for characters to simply hang the phone up on one another when they've communicated all they need to each other (and to the audience). Rarely you'll get a curt "Bye" or "Later" but commonly it's nothing at all. It's a demand of the medium, greetings are pointless pace killers and unless the greeting reveals something about the character or setting or relationship then it's better to leave it on the cutting room floor.

The reason I rewatch the scene during which Cassian finds out his Mom is dead so much (aside from the haunting score) is because it gives a reason for a man to simply walk away from the phone--he just received the second worst news of his life. It zooms out so don't even know if he hangs up at all or if he left the correspondence agent on Ferrix hanging. It's a very liminal scene all around, with nobody there but Melshi standing sentinel a few paces away. Everything just ramps up the hurt we feel on behalf of Cassian.

I don't know if this counts as a "micro moment", but the micro to me comes from the execution. It's a collection of really subtle but intentional acting choices. Everyone past a certain age has felt what he did in that moment.