Is there an option to send a fax to an email address or a Web portal instead of going through Salesforce?
You can setup automation to email a received fax with the attachment. This requires a VisualForce email template so that it can include the attachment that is related to the Received Fax record. The creation of a new Received Fax record would trigger the automation.
With how the app is built, you can only access the faxes in Salesforce. You could setup a Salesforce Community, Partner portal, customer portal, or force.com license for $25/month for specific users. You could also give these users a login to your Salesforce and setup a limited profile that only gives them access to what they need.
If you need more guidance on how to create this process or if you would like us to configure it for you, we offer premium support as a paid service.