An analysis and background information are provided to public safety system administrators and communications systems planners on the different types and capabilities of LMR subscriber units (mobile and portable radios). The report matches the specifications of these products to applicable public safety physical, functional, and interoperability criteria. It is intended to serve local, State, Federal, and tribal pubic safety agencies managing or considering the procurement of LMR subscriber units. A detailed analysis is provided of the physical, functional, and interoperability features of mobile and portable radios in the public safety marketplace today. These analyses are based on criteria incorporating the user needs of public safety personnel and the public safety operating environment. Background information is provided regarding the characteristics of the different frequency bands employed by public safety agencies, system infrastructure technologies, system signaling protocols, relevant standards, and the various proprietary systems currently available and used by public safety agencies. Public safety administrators, procurement officials, and communications system planners are provided with descriptive information, comparisons, and operational considerations to foster appropriate decisionmaking and procurement processes for new or replacement mobile and portable radio equipment. Communication trends in the public safety environment are discussed, as well as opportunities that may present themselves with continuing technical advances and the application of emerging standards. 8 footnotes, 7 appendices