NVOCC (Non-Vessel-Operating Common Carriers) or NVO (Non-Vessel Operators) or sometimes called Box Operators are those carriers who offer port to port services exactly as Main Line Operators (MLO) by issuing their own Bill of lading but deep down they do not operate vessels but own the fleet of containers and fill the slots with Vessel Operators (VO).
NVOs kept playing a major role in logistics history as one of the major players in carriage of goods by sea among other service providers i.e....
https://container-news.com/nvocc-the-underrated-service-provider-in-global-logistics/