In a satellite communications network, local pools of available carriers are assigned to each ground earth station GES by a network channel management station NCMS, which stores a pool of unallocated carriers. If the number of unused carriers in a local pool falls below a predetermined level, additional carriers are allocated from a regional pool in the network channel management station NCMS. If the number of carriers in a local pool exceeds a predetermined level, the excess carriers are released to the regional pool so that they can be allocated to local pools in other ground earth stations GES.