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We have implemented a reliable outbound fax service that we believe provides the most reliable fax service in the VoIP industry. We assure end-to-end T.38 delivery to our PRI-connected FAX fax server to ensure your faxes hit the PSTN without improper transcoding and conversions. Our SIPStation FAX fax service is available for the lower 48 US only and is delivered as a metered service at a cost of 2.4 cents per minute for outbound calls. Inbound T.38 calls are part of your normal trunking service and do not carry a per-minute charge.  In order to gain access to the fax service, you need to be set up for the "metered services" option in SIPStation. Metered services deduct funds from your reserve account as described in our wiki "How Metered Service Works."


Global Fax Prefix

If using Fax Pro Overview in FreePBX to send outbound faxes from the User Control Panel (UCP), UCP can automatically add a fax prefix. The advantage of this is that UCP users would not have to remember any prefix when faxing from UCP. Instead they would just need to dial a 10- or 11-digit number. UCP would add the global prefix to the beginning of whatever the user dials. When setting this up, you just need to keep in mind that the resulting combination needs to match something in an outbound route for fax. Also keep in mind we need to receive *323 at the beginning of a 10- or 11- digit number in order for outbound faxing to work in SIPStation.


In FreePBX, go to Settings → Asterisk SIP Settings → Chan SIP (right-hand side). Scroll down to Audio Codecs and make sure T38 Pass-Through is enabled.

Configuring Fax


Settings in


PBX Modules

Full For fax configuration of faxing, including UCP setup and detecting faxes on incoming routes, is beyond the scope of this wiki. However, here is some basic information on some options you can configure.

You will find these basic options when you go to Settings → Fax Configuration.

Here you can set:

  • Fax header
  • Station ID
  • Outgoing e-mail address
  • E-mail address where incoming faxes are received
  • Error correction mode (Set this to No when using VoIP)
  • Maximum & minimum transfer rates (Set this to at least 4800 to avoid problems. Adjust the maximum as needed to avoid incomplete faxes. 9600 is a good starting point for maximum rate.)
  • Paper size
  • Cover page options such as logo, company name, address, phone, web site, and footer (You can also preview the cover page)
  • Global fax prefix (Described earlier in this wiki)
  • Retry count and failure notification e-mail
  • Local storage limits

instructions, please visit the appropriate wiki below: