Method, apparatus, and computer program product embodiments are disclosed for managing coexistence of secondary users in RF spectrum. An example embodiment includes receiving, by a coexistence manager, information indicating that a candidate wireless network served by another coexistence manager may interfere with a wireless network served by the coexistence manager; determining a location related to the wireless network served by the coexistence manager; transmitting a request message to the other coexistence manager, indicating the location and requesting an estimate of a transmission signal level at the location caused by the candidate wireless network; receiving from the other coexistence manager, a response message including information indicating an estimated transmission signal level at the location caused by the candidate wireless network; and determining whether the candidate wireless network interferes with the wireless network served by the coexistence manager based on the received estimated transmission signal level.