The American Public Switched Telephone Network (PSTN) employs time-division multiplexing (TDM) technologies and services that are nearing end-of-life, or “sun-setting.” Federal government agencies remain significant users of TDM services, including both copper-based analog telephone lines and older access technologies such as T-1 that are used to connect government locations to public networks. Many of these services are procured through GSA contracting programs that will be replaced by the new GSA Enterprise Infrastructure Solutions (EIS) program. Thus, the EIS source selection process provides a timely opportunity for replacing legacy TDM services. While TDM services are still available commercially and can be provided via EIS contracts, there is no assurance that like-for-like legacy telecom services will be available at current prices or at current locations moving forward. This uncertainty and risk affects all government users presently served by TDM-based offerings. Federal agencies should avoid these risks by adopting IP-based or wireless solutions where feasible when transitioning to EIS. Agencies should plan and budget for transformative solutions when developing EIS solicitations or otherwise seeking replacement for TDM services. This should include expert assistance to conduct requirements analysis, assess technical options, and make recommendations for transformative solutions.