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How does it work?

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 server to ensure your faxes hit the PSTN without improper transcoding and conversions. Our SIPStation 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."

How do I sign up?

  1. Log in to the SIPStation Store at


  1. Click on the "My Account" tab in the menu at the top of the page.

  2. Scroll down toward the bottom "Metered Services" section.

  3. Enable T38 Faxing by changing the On/Off switch to "On" (green).


Outbound T38 faxing in SIPStation is a pre-paid, metered service. When you enable T38 faxing, "Top Up Settings" are also automatically enabled as shown above, and your account will be charged the Top Up Amount. This amount will be placed in your reserve account, and the per-minute fax charges will be withdrawn from that balance. You can click the "Update" button if you need to change the default amounts. For more information on Top Up Settings please view our wiki "How Metered Services Work."

Once signed up, how do I make outbound T.38 fax calls?

All outbound T.38 fax calls need to be sent to us as *323 and then either a 10-digit or 11-digit number. For example, if you wanted to send a fax to 5555551234, you would send the call to SIPStation as *3235555551234. The easiest way to do this is to set up an outbound route in FreePBX called "Fax."  Then add a simple prefix such as 9.  So your users would dial 95555551234. You would want the outbound route to strip (remove) the 9 and add the prefix *323 as shown below.


Don't forget to drag the Fax outbound route toward the top of your route list.

If using Fax Pro in FreePBX to send outbound faxes from the User Control Panel (UCP), you can have it automatically set the 9 prefix for you, so users won't need to add the 9 when dialing within UCP.  You do this in the Fax Configuration module in FreePBX.


Please note, you must have Asterisk setup to Handle T.38 at the Asterisk level. We are not able to offer technical support for this. FreePBX does have an option to enable T.38 in the SIP Settings module, but you also need to make sure Asterisk is compiled for T.38.

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