Spoiler warning: Plot and/or ending details follow.
A communications center is an installation designed as a central location for sending and receiving radio transmissions.
Following the massacre on Tarsus IV, the survivors of the Starfleet Outpost made their way to the colony's communications center. With the help of Security Force officer Jacob Clancy they gained access to the center. Lieutenant Commander Gabriel Lorca was able to then use the center's equipment to hail the USS Narbonne and bring them up to speed on the colony's current status. (DSC novel: Drastic Measures)