Earth Cargo Service
The Earth Cargo Service (or ECS) was the agency in charge of managing Earth's interstellar cargo fleet, prior to the formation of the United Federation of Planets in 2161. 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.[1]
During the period following First Contact, J class vessels were the first series production of freighter to become available for civilian commercial use. Upon the Starfleet development of the Hercules class (Y class in civilian use), the ECS began phasing out J class ships[2][3]
Notes
The reliance upon J and Y class vessels has been adapted time-wise from the Memory Alpha and Beta web sources.