The Cortex

The Cortex is the internet of the 'Verse and much more. Everything goes through the Cortex, it's the ultimate evolutionary product of the internet, phone service over internet, video on demand, etc. All communication, TV shows, phone calls, data transfers, movie and data downloads takes place through the Cortex.

After some consideration of the effects, and going by the movie Serenity as a guide, I decided the Cortex uses faster than light, practically instantaneous communication. The 'Verse has a great deal of gravity manipulation technology, so I'm going with the idea that the Cortex uses gravity waves and they are faster than light. There are signal boosting stations to relay Cortex signals from the core worlds to the rim. Small ships like the Firefly class have short range transmitters, large military vessels have the power to contact anyone in the 'Verse.

Messages and calls on the Cortex are called "waves", probably a reference to the Cortex being a gravity wave transmission network. In the movie, they say "broadwave" instead of broadcast.

Examples:
Every piece of live Cortex communication is real time (Mal talking to Patience in the pilot; Inarra talking to Nandi in "Heart of Gold"; Inarra calling Mal, the crew calling Mr. Universe and Mal talking to the Operative in the movie) with no lag. And Mr. Universe does long range hacking from his moon to Beaumonde and relays it live to the Serenity.

When Mal calls Patience, he comments: "We should be close enough for vid." It's not lag time, its transmitter range that he's referring to. That's why in "Out of Gas", they can't call for help. The transmitter on a Firefly is just too short ranged to reach a Cortex relay station and get the message out.