Guardians of the Stars
Most communication has changed very little, our best technologies still mostly work in the EM spectrum over a wide variety of frequencies. Other than EM we have a broad spectrum of lasers as well allowing faster and more secure, but more difficult, directed communications.
The most advanced and fastest method of communications is the Subspace Pulse Generator (SPG). These devices send a simple wave in an omnidirectional pulse from the device through subspace and travel at FTL speeds with a distance measured by the amount of power put into the subspace effect (typically 1-10 ly). Because of the power requirements and the size of the required hardware for transmission only large bases and stations can transmit. Any ship with subspace sensors however can receive such a message.
The SAN has developed a new much smaller directional FTL communications system called a Subspace Burst Transmitter (SBT). Much like an SPG, they have a limited data transmission rate of 1kb per second. They also have very limited range measured in light minutes and require large amounts of power to use, making them only usable outside of combat. It takes messages 1 second per light minute in travel time.