There are numerous Internet services that will bridge 2020s technology to 1990s technology (actually, the fax machine dates to the 1920s, with earlier antecedents). My favorite, because it really is free, is FaxZero. Note that there is an option on the main page that brings up the fax numbers of Senators and House members.
Note: Senator Padilla doesn’t receive faxes. No word on whether his office can read cursive.