An online fax service; a pdf document to fax; sending a fax – through email. do it the old way using fax machines. let’ s dive right in to explore how to send a pdf to a fax number for free. faxing the “ old” way allows you to send pdf fax from a physical fax device. when ready, click the send button. the process is tedious, but here is how it works. an online fax service will let you fax a pdf very much the same way that you attach an email to a document. the pdf is attached. print out the pdf. here pdf fax are some methods you can use to send pdf as fax. most online fax services allow a user to send a fax through email. what you’ ll need. click the settings icon to access options to schedule the fax, retry if it fails, email recipients a pdf of the fax, and optimize the document for faxing. how to fax a pdf online.