In addition to rules for faster than light travel, another thing that needs to be covered with specific rules is how communication is supposed to actually work. There’s plenty of people who lament how mobile phones make lots of investigation and mystery plots unworkable, and how such a simple and important technology absolutely has to be included in any new science fiction works. But after thinking about the practicalities in this area, I think it’s actually very plausible to have pretty limited communication in the way typically seen in older and more pulpy space adventures, even when you consider that the societies should have no barriers to create cell phones.
While my setting has Hyperspace travel to travel faster than light between star systems, I have decided that it doesn’t have faster than light communication. Ships in hyperspace are already treated as effectively blind, so why not also treat them as deaf?
The highly developed home systems all have very advanced and sophisticated local internets. On the homeworlds themselves, people have internet as we are used to. Outposts on other planets, moons, and asteroids in the system also have access to this net, but with severely limited bandwidth and a time delay that can be on the scale of hours. People on these outposts can download text, audio, and even video at slow speed and reduced quality, but instant communication is limited to other people within the same outpost. For communicating with anyone else, they have to write emails, or record audio or video messages. Because these system-wide networks are separated from each other, they all are effectively their own environments with their own content.
To transfer information between system networks, the data has to be transmitted to a mail barge, which stores it on hard drives, then makes Hyperspace jumps to its intended destination, where it feeds the information into the local network. This takes several days, and storage space on these barges is limited and therefor comes with non-trivial costs. Mail barges are used to deliver written or recorded messages like mail, and files that have a long lasting relevance like books and movies. They also carry interstellar news between the big galactic news networks, but the local news of one system usually have little relevance for the people of other systems. The home systems have hundreds of mail barges going back and fort between them every day, but colonies might only see a single barge from their home system per day, and in many frontier worlds barges only arrive once per week or per month.
For characters to access one of these homeworld or colony networks, they have to fly there in their ships themselves, or send out a document request with a mail barge and wait for delivery with the next barge coming back, which can take weeks.
The homeworlds all have planet-wide mobile communication systems. These are good enough to gain signal access pretty much everywhere of the planet except for the poles on some less advanced worlds. Colonies are usually only the size of a single city or small country, and these have their local communication networks based on signal towers throughout the colony. The range of these usually only covers a couple of kilometers. Beyond that range, people won’t be getting any signals. Most worlds have compatible networks that allow visitors from other systems to connect to it by getting a short-term account for usually a week or a month on arrival when they go through customs or register their ships for docking. (It’s not that expensive and included in the docking fee when PCs arrive on a new planet.)
Smaller colonies and outposts don’t have even that and instead rely entirely on local wireless networks. Visitors usually only get access to these if they are staying with locals or rent a place to sleep. For communication outside the colony grounds, people have to use primitive but fully serviceable radio comunicators that are powerful enough to transmit signals over several kilometers. Most people traveling on space ships carry one of these with them all the time as they allow them to communicate with each other and their ship completely independent of local infrastructure within a limited range.
Most ships have communication systems to both log into local networks and communicate through radio with controllers on planets and other ships over distances in the millions of kilometers. But unless ships are really close to each other or in orbit around a planet there will be a considerable time delay.
Communication for Players
PCs can always communicate with each other through their radio comms within ranges of several kilometers and even their ship in orbit if it is right overhead.
On homeworlds and major colonies, PCs also have access to the local network within urban and developed areas.
There is no practical communications between systems for PCs, with the exception of using the mail which will take days or weeks to get a reply.