There are many marketers that use fax advertisements to reach out to existing and potential clients. In fact, they use written advertisements and fax machine is just a tool.
If advert is targeting future, prospective clients, then it’s the very similar approach as telemarketing. Goal is sending out a large number of written ads to fax numbers hoping that will bring new clients. People usualy don’t like receiving this kind of fax messages. It’s like spam e-mails but kind of worst since you loose some time and paper receiving unwanted message.
But if messages are sending to existing clients, that pre-approved receiving fax advertising, that could get some results. Although, in this era of internet, that kind of advertising seams loosing track.