How does the information get to the online fax service?

For outgoing faxes, typically you log into a website, enter the required data (name, phone number, coversheet text), and upload your document (most likely a .PDF file). Once you confirm all the information, press the SEND button on the webpage and this should start the process to send the fax. You are done at this point and do not need to stay online to complete the send. For incoming faxes, you are assigned a specific phone number and any faxes received on that number are forwarded to your email address as an attachment (typically .TIF or maybe .PDF). When you open the message, you will then need to download and open the attachment to view it.