PhelboreK-casts...
... are very much an official aspect of ED lore, since they are mentioned in several of the official novels. They are depicted as (more or less) instant two-way comms, either with or without a holographic image of the correspondents. There's also a recorded messaging facility, rather like Instagram.
How k-cast works is never explained; I imagine there's a system of relays built into starports all over the bubble, with satellite beacons spread out in uninhabited systems as they are visited. But, as Matt says, that really doesn't matter!
Last edit: 29 Jul 2017, 1:45pm