A UNICOM (universal communications) station is an air-ground communication facility operated by a non-air traffic control private agency to provide advisory service at uncontrolled aerodromes and airports and to provide various non-flight services, such as requesting a taxi, even at towered airports.
From an ICAO perspective, UNICOM, historically most commonly provided by flight service stations, is an implementation of FIS.
[3] UNICOM is employed at airports with a low volume of general aviation traffic and where no control tower is active.
Under this protocol, aircraft may call a non-government ground station to make announcements of their intentions.
Pilots who join the frequency later can request field advisories, which may include "weather information, wind direction, the recommended runway" and any previously reported traffic.