No matter what you do, its fax, so just a phone call. You have to work the issue from both sides in order to do anything security related, and the devices/services need to also be compatable.
I doubt there is any way to do this for a one-off fax
I'm applying for a mortgage and am at the point in the process where email won't work and need to start faxing some documents. I've previously used online services to send faxes for free but am worried about using them to send financial documents containing my SSN etc. Any services you would recommend to do this from my computer? I'm okay with paying 5-10 cents a page if needed.