(a) All issuing carriers that file tariffs are required to file tariff publications electronically, if practicable.(b) All tariff publications shall be filed in a manner that is compatible and consistent with the technical requirements of the Electronic Tariff Filing System.(c) Tariff publications which must be filed in hard copy format should be submitted according to the procedures set forth on the web page of the FCC's Office of the Secretary, https://www.fcc.gov/secretary. 83 FR 2557 , Jan. 18, 2018