An approach is provided for cooperatively sharing spectrum. A threshold value associated with an acceptable level of interference to a first radio network is determined. A beacon message specifying the threshold value is generated for transmission from the first radio network to one or more nodes of a second radio network that is configured to exchange traffic for mobile services. The first radio network and the second radio network share spectral resources including adjacent bands for the respective radio networks, and the beacon message is used for controlling the level of interference to the first radio network caused by the one or more nodes of the second radio network.