EXHIBIT-21.1 - ------------ Significant Subsidiaries of the Registrant State or Country Of Formation ------------- Teligent Services, Inc. Delaware Teligent Telecommunications, L. L. C. Delaware Teligent Communications, L. L. C. Delaware Teligent of Virginia, Inc. Virginia Teligent License Company I, L.L.C. Delaware Teligent License Company II, L.L.C. Delaware FirstMark Communications, Inc. Delaware Association Communications, Inc. Washington OMC Communications, Inc. Maryland Easton Telecom Services, Inc. Ohio BackLink, L.L.C. Delaware JTel, L.L.C. Delaware KatLink, L.L.C Delaware Associated Communications Deutschland GmbH Germany