Form 477: The FCC has extended the deadline for filing Form 477 until March 8, 2019 to report data as of December 31, 2018. Here is a link to the FCC’s Public Notice announcing the extension: http://www.berrybest.com/relay14.asp?df=013119&pf=DA-19-33A1.pdf
According to the Public Notice, the filing portal is open and is accepting Form 477.