There is provided shared use of licensed frequency spectrum in a mobile communications network, while maintaining confidentiality between the license holder and the licensee. Geographical information on availability of licensed frequency spectrum for shared use is obtained. A site map of a mobile communications network is obtained. The site map includes locations of sites, where wireless access to the mobile communications network is provided. A configuration of frequencies for the sites on the basis of the available licensed frequencies for shared use at each location of the sites is determined.