Starfleet Academy Courses. Subspace Communication: The speed of subspace messages varies considerably depending on the technology used. For example, in the 2260s, a subspace message from the Romulan Neutral Zone took three weeks to reach Starfleet Headquarters, while a century later, at the same distance, subspace communications were virtually real-time. See: TOS: "Balance of Terror," Star Trek Nemesis. Star Trek Starfleet Command | Starfleet Academy

Starfleet Academy Courses. Subspace Communication: Ship commanders also use subspace communication to transmit reports on their various missions to Starfleet Command, solicit suggestions, make requests, monitor the status of other ships, and issue other commands. See: ENT: "Shockwave"; TOS: "Balance of Terror"; Star Trek II: The Wrath of Khan; TNG: "The Best of Both Worlds"; VOY: "Friendship One"; etc. Star Trek Starfleet Command | Starfleet Academy