A domain proxy receives a request from a base station for allocation of a first portion of a frequency band to support cellular communication in a geographic area that is indicated in the request. The frequency band is available for exclusive allocation to an incumbent device. The base station is required to vacate the first portion of the frequency band in response to the incumbent device arriving in the geographic area and being allocated a second portion of the frequency band that overlaps with the first portion. The domain proxy accesses a policy for the base station from a database and, based on the policy, selectively provides the request to a spectrum access server (SAS) that is responsible for allocating portions of the frequency band.