How Would an Ansible Work? (Ender's Game)

I finished reading Ender's Game a while ago, but this lingering thought has been bouncing around in my head for a while: How would the ansible described in Ender's Game actually work?

Potential spoilers ahead.

For those of you who haven't read Ender's Game, the ansible is a machine which is capable of sending/receiving data at/nearly at the speed of light. It allows for communication across vast distances, which is super useful for space-bearing civilizations.

Note that the term "ansible" has been around before Ender's Game was written, so we are just use Ender's Game as a reference.

In the book, while Ender is traveling around on a spaceship, he is able to talk to his brother on Earth. Due to relativity, Peter (his brother) ages faster relative to Ender, and dies while Ender is still young.

With that in mind, what would a zoom call look like over ansible? If you have a constant stream of communication between 2 parties, were both parties experience time differently relative to eachother, would one experience it in slo-mo? Would one be faster then the other? Would the communication itself slow down or speed up to "sync" with the time relative to the person receiving the message?

This technology can't exist (probably), so trying to rationalize it in terms of our current understanding of physics is futile.

In the book, we only came across this technology because the aliens brought it to us. It goes without saying, but there is a very low probability that we would've came up with something similar for a very long time.

The best (and only) solution is to ponder the cool ways we might use such a technology, knowing that we almost certainly will never be able to use it.