ComStar has a monopoly on instantaneous interstellar communication, but NOT on interstellar communication in general. The HPG network is too limited for that. It requires an immense amount of energy to transmit signals between the stars, and the bit-rate of transfer is really too low for anything but text messages to be affordable.

A short text message sent to a nearby star could be as little as 1 C-bill, but a long text sent from one end of the Inner Sphere to the other could be as much as a Red Blake (100 denomination C-bills have a reddish color and have Blake on one side, hence the name).

GM Note: Doesn’t sound that expensive, until you realize 1 C-bill is about 10 dollars in current money. Who wants to spend 10 bucks or more just to e-mail their sister? Or a 1000 dollars to download Shakespeare’s works?

If you can afford it, you can get the bandwidth you need to send images, or even live footage. Depending on the number of nodes involved, transmitting a simple image could cost between 10 to a 100 C-bills. If it’s a hi-res image the price could be as high as ten times that (getting a good compression tool is recommended).

A lot of government and private communication instead takes the form of messages (text, images and whatnot) sent by courier ship. These are not necessarily dedicated courier ships – any old commercial dropship will do. Ship owners make a little money by acting as couriers. For the most part these mailmen are as inviolable (at least publicly) as ComStar – if you start screwing over basic postal services, civilization threatens to break down. You have to pay for these services too, but the cost is just a fraction of what ComStar charges. Sending some hi-res vids of you baby drooling to your sister isn’t going to cost you more than a stamp would, if that.

The way it works is that any dropship leaving a planet will query if there is an outgoing data dump for his destination – or anything further “downstream”. If it is, it will download it and the ship’s owner gets paid for the service. Upon reaching the jump point the ship will query other dropships and jumpships present, and transfer a copy of relevant messages going places they are headed (and pick up any messages they might have going forward). The process is repeated with every jump, until finally the dropship reaches its destination. If it went several jump, chances are great it picked up some more messages along the way. This way messages propagates out through space at a fairly good rate, but can still take weeks or even months to reach distant places.

Alternatively, priority messages can be radioed directly to a jumpship at one of the system’s jump point. This cuts the transfer time from planetary surface to the jump vessel, but dumping a great deal of data between a planet and a spaceship many light minutes away increases costs and greatly limits the bit-rate (some core worlds even have repeater sats orbiting the sun to boost such signals, but it’s rare). It’s cheaper than ComStar, and faster than by dropship, so it’s worth considering.