1. A method, comprising: configuring a plurality of network management domains (NMDs) within a network management system (NMS) of a host communications network (HCN), wherein each NMD is associated with a virtual communications network (VCN) provisioned within the HCN, and wherein the HCN provides outroute and inroute capacity for the VCNs by means of one or more segments of communications spectrum; configuring a plurality of outroute capacity partitions via one or more outroute network elements of the HCN and configuring a plurality of inroute capacity partitions via one or more inroute groups configured within one or more inroute network elements of the HCN, wherein each outroute capacity partition supports a respective level of outroute capacity and each inroute capacity partition supports a respective level of inroute capacity; allocating one or more of the outroute capacity partitions and one or more of the inroute capacity partitions to a first VCN to provide a fixed level of outroute capacity and a fixed level of inroute capacity to the first VCN; and configuring one or more operator classifications within the NMD associated with the first VCN, wherein each operator classification specifies a set of network operator capabilities and permissions allocated to one or more virtual network operators assigned to that classification.