The communities cited in the handbook were selected from among the 10 jurisdictions across the United States involved in a pilot grant project that provided the communities with ACU/TRP-1000 systems, which is a useful communications device for those who must establish a link with other local, State, and Federal agencies at the scene of multi-agency response incidents. The ACU/TRP-1000 system provides radio interoperability during incidents or events that require communications between diverse organizations that use different radios and/or different frequencies. The introduction to the handbook describes grant program support and lists preferred technical capabilities for persons assigned to operate the ACU/TRP-1000. The second section of the handbook provides background information on multiple agency interoperability communication, along with basic information on the ACU/TRP-1000 Gateway Switch/Interoperability Communications System, including a general overview of its operation. The third section outlines the basic set-up and initial operating procedures of the ACU/TRP-1000 Interoperability Communication System. This is followed by a section that presents findings on lessons learned from a survey of jurisdictions that have had operational experience with the ACU/TRP-1000 Interoperability Communications Systems. The concluding section of the handbook describes set-up and deployment by jurisdictions that are using the ACU/TRP-1000. These system models show the potential for achieving a high performance system. Based on these reviews, new users will be better prepared to set up and operate comprehensive systems that use the full capabilities of the ACU/TRP-1000. 10 figures and appended list of points of contact and a list of participating jurisdictions