Hotline
A hotline was a direct line of communication established for a specific purpose, such as an emergency.
In 2266, when a stranded Hikaru Sulu called the USS Enterprise from the surface of Alfa 177 for an update on the transporter situation, Captain James T. Kirk answered, much to the helmsman's surprise. He quipped, "Hot line direct to the Captain. Are we that far gone?" Kirk assured him that he was just minding the comms while everyone else had the afternoon off. (TOS: "The Enemy Within")