Method for switching between network configurations in a radio access network shared by a plurality of mobile network operators, wherein radio spectrum allocated to the mobile network operators is split into at least one carrier and wherein two network configurations for sharing the radio access network are defined: - a pooled configuration by which all the mobile network operators share the, at least one, carrier into which the radio spectrum is split; and - a dedicated configuration by which the at least one carrier comprises a plurality of carriers, and each mobile network operator has at least one dedicated carrier assigned from the plurality of carriers into which the radio spectrum is split; the method being characterized by comprising: - allocating a single carrier to traffic of all the mobile network operators, which share the single carrier in the pooled configuration; - measuring an indicator of traffic load in the shared single carrier, - comparing the measured traffic load of the single carrier with a threshold and only when the measured load exceeds the threshold, - checking availability of pre-empting radio spectrum to split it into a plurality of carriers and if said pre-emption is available, - switching from the single carrier in the pooled configuration to the plurality of carriers into which radio spectrum is split for allocating traffic of the mobile network operators in the dedicated configuration. - a pooled configuration by which all the mobile network operators share the, at least one, carrier into which the radio spectrum is split; and - a dedicated configuration by which the at least one carrier comprises a plurality of carriers, and each mobile network operator has at least one dedicated carrier assigned from the plurality of carriers into which the radio spectrum is split; the method being characterized by comprising: - allocating a single carrier to traffic of all the mobile network operators, which share the single carrier in the pooled configuration; - measuring an indicator of traffic load in the shared single carrier, - comparing the measured traffic load of the single carrier with a threshold and only when the measured load exceeds the threshold, - checking availability of pre-empting radio spectrum to split it into a plurality of carriers and if said pre-emption is available, - switching from the single carrier in the pooled configuration to the plurality of carriers into which radio spectrum is split for allocating traffic of the mobile network operators in the dedicated configuration. - allocating a single carrier to traffic of all the mobile network operators, which share the single carrier in the pooled configuration; - measuring an indicator of traffic load in the shared single carrier, - comparing the measured traffic load of the single carrier with a threshold and only when the measured load exceeds the threshold, - checking availability of pre-empting radio spectrum to split it into a plurality of carriers and if said pre-emption is available, - switching from the single carrier in the pooled configuration to the plurality of carriers into which radio spectrum is split for allocating traffic of the mobile network operators in the dedicated configuration.