Modifying your Sfax Download Service
Login to Sfax using an Administrator (or higher) ruser
Once logged into Sfax, select the Settings button
From there, select the Manage Users tab and then find the Sfax Download Service user (the name will typically include winserv for identification).
Assign any additional fax numbers that need to be attached to the user by checking off “Incoming” for that line
After the user has been attached to the fax line, you will need to access the machine where the Sfax Download Service is installed. Once there, open the Windows Services panel and find the “FaxDownloadService”. Once this has been located, stop the service by clicking on the Stop button on the left panel. 
After stopping the service, you will need to browse to c:\SfaxFaxDownload\ on the machine, and Edit the config.xml file. Please note, the config.xml does not contain any formatting and will be displayed as a single large mass of text in standard editing applications (Notepad, Wordpad, etc…). 
The config.xml will look similar to as follows, with your specific information entered into the cleared fields.
Once in the config.xml file, you can adjust the following settings:
OutputFormat PDF or TIF
OutputFilenameFormat
| Option | Format | Example |
| Default | FaxId | (2150310165103980593) |
| Option1 | (Last 4 of recipient fax number)_(Fax)(Date)(Time)_(Number of Pages) | (4028_03102015115800664783_1) |
| Option2 | (Last 4 of recipeint fax number)_(Date)_(Time)_(Number of Pages) | (4028_03102015_120100581558_1) |
| Option3 | (Last 4 of recipeint fax number)_(Date)_(Time)_(Last 5 digits of FaxID) | (4028_03102015_120400_80350) |
| Option4 | (CSID)_(Date)_(Time)_(Last 5 of FaxID) | (8889744028_03102015_121003_80723) |
| Option5 | (Sender Fax Number)_(Date)_(Time)_(Last 5 of FaxID) | (8889744028_03102015_121400_80941) |
To add an additional number, you will need to add the additional line(s) by copying one of the existing number entries and then updating the information to the new number and download location.
StoragePath (this can be either local [preferred] or UNC) for each associated fax line (the closing \ is necessary to preserve folder structure and file naming choice)
ie: (local) c:\StoredFaxes\ or (UNC) \\server_name\StoredFaxes\ 
Once you have updated the config.xml, you will then start the FaxDownloadService again, which will reset the 3 minute download cycle.
The service will then download any faxes that are new any of the numbers associated to the Sfax Download Service, that have not already been downloaded previously.