Labex FIRST-TF is a national program, led by the CNRS and supported by 9 other institutions, and organized around a network of some 60 laboratories, manufacturers and other structures with a keen interest in time-frequency activities. It supports the development of research projects, technological activities and training, as well as actions to promote and coordinate these activities. FIRST-TF covers a wide range of subjects and applications: clocks, oscillators and synchronization techniques, fundamental science, positioning and navigation, sensors, geosciences, health and the environment, and the role of time in art, literature and the human and social sciences. Intertwined with the FIRST-TF network, the Equipex REFIMEVE+, supported by Université Paris 13 and based on the RENATER infrastructure, is a fiber-optic network for disseminating a frequency reference in the optical domain with extreme precision. It enables connected laboratories to perform frequency calibration in a measurement time 10,000 times faster than with a GPS signal. Strongly connected to the FIRST-TF network, the Equipex Oscillator IMP, supported by the FCS Bourgogne Franche Comté, is a platform dedicated to the characterization of temporal fluctuations and frequency stability for short measurement times. It enables significant improvements in measurement resolution, both for accredited service activities and for the R&D needs of agencies, research institutes and private companies.