Long range communications in TOS.

[Candleicious Ghost]

Well in TNG they did come up with an explanation for how the ship can talk to Earth and the conversation is almost instantaneous because of the subspace comms system which spans known space.

But what about TOS they never really did address this in TOS did they?

 

[mithril]

the details of long range comms was never really talked about it iirc. and when communications got brought up at all, the general impression was that communications from the ship would take a long time to reach command, and then a long time to come back.

Enterprise establishes that deploying relay's was a standard part of the NX-01's mission, so presumably the NCC-1701 also deployed such relays as they explored. i can only assume though that the farther out you are (and the more rela's you have to send the signal through) the longer it takes, making realtime comms to exploration ships like the enterprise more difficult in that era.