The Earth Cargo Service (or ECS) was the primary operating agency governing the operations of Earth-registered interstellar cargo transport vessels in the first half of the 22nd century. It was governed by the Earth Cargo Authority. Ships needed a license to operate under the ECS, which in some cases could be lost if a rendezvous was missed.
The crew of these ships would spend years traveling from one planet to another; whole generations of these "boomers" grew up in space, and the ownership of ships often passed down family lines.
Among the planets visited by the Earth Cargo Service were Draylax, both Teneebian moons, Trillius Prime, Vega colony, Deneva colony, and presumably Earth. (ENT: "Broken Bow", "Fortunate Son", "Horizon") Trade also existed with the Demerians and the Orions. (ENT: "Horizon")
It seems probable that other Earth colonies, like Alpha Centauri, were serviced as well. At some point, the
Horizon made contact with a Deltan ship, and Captain Mayweather visited Neubilia Prime, but it is unsure if either event was in the context of formal trade. A Y-class ship, a type known to be used by the ECS, was also seen in orbit of Verex III.
In the first draft script of "Fortunate Son", it was established that ECS regulations prohibited the holding of prisoners.