Glessner services thousands of households in Maryland, Virginia, West Virginia, Pennsylvania and the District of Columbia, earning it the reputation as one of the most highly respected security and communications companies in the region. We service such clients as the United States Army, United States ATF, United States Coast Guard, National Park Service, United States Department of Energy, Air National Guard, Department of Social Services, MCI/MCTC and Federal Aviation Administration. We are bonded and insured.