An apparatus, system, method and program detect and reduce interference in cell sites of a wireless communications network. A cell site from the cell sites of the wireless communications network is selected and signal code power measurements from mobile devices in the cell site are received so that the sources of signals being transmitted to the mobile devices can be determined. Interfering sources are determined based on the signal code power measurements and the active set of sources for the mobile devices. The signal code power measurements are summed and ranked, and interfering transmitters associated with the ranked signal code power measurements for the interfering sources are determined. The same procedure is repeated for all cell sites of the wireless communications network, and the transmitter that is an interfering source for the highest number of cell sites is selected as a problem (interfering) transmitter. The parameters of the problem transmitter and the corresponding antenna are altered and performance of the wireless network in a critical zone around the problem transmitter and interference in the cell sites interfered by the problem transmitter are monitored. Altering of the parameters of the problem transmitter and the corresponding antenna is performed continuously until a desired interference reduction is achieved in the cell sites interfered by the problem transmitter.