A method and apparatus are disclosed for setting an initial transmit power level of a deployable network that overlaps in coverage with a WAN. Multiple transmit power levels are determined. For each transmit power level, a geographical coverage area of the deployable network at an incident is determined based on a signal propagation model, a first set of mobile devices is determined that are within the geographical coverage area and that are involved in responding to the incident, and a second set of mobile devices is determined that are within the geographical coverage area, that are not involved in responding to the incident, and that may be interfered with by transmissions of the deployable network. A transmit power level of the multiple transmit power levels then is selected as the initial transmit power level based on the first and second sets of mobile devices determined for each transmit power level.