Our Power-T.38 SIP trunks are officially certified for use with Dialogic SR140. Click below to download Dialogic's official document outlining the specific SR140 configuration settings required to connect to Power-T.38.

Download SR140 Config Guide

Alternatively, follow the screen shots below to configure GFI FaxMaker to use T38Fax.com:

1. Launch “FaxMaker Configuration Wizard.

2. Select the “Brooktrout SR140 Software Fax over IP” option under the “Brooktrout by Dialogic” fax hardware type and click “Next” to continue.

Should you need to install and license the SR140, see the following URL for details:


3. Launch the “Brooktrout Configuration Tool” from “GFI FaxMaker Brooktrout TR1034 Drivers” in the Start menu.

4. When the “Brooktrout Configuration Tool” wizard appears, click “Advanced Mode.

5. In Advanced Mode, select the “SIP” node under “IP Call Control Modules” and then navigate to “IP Parameters” tab in the right pane.

6. Input the following values in the fields below:

  • Primary Proxy Server: sip.t38fax.com
  • Primary Registrar Server URL: sip.t38fax.com
  • From Value: sip:YOUR_DID@sip.t38fax.com

=== Substitute YOUR_DID with your T38Fax.com DID ===

Click “Show Advanced >>” to show the remaining settings and then input the values below:

  • Primary Registrar Server Address of Record: YOUR_DID@sip.t38fax.com
  • Primary Registrar Server Username: YOUR_DID
  • Primary Registrar Server Password: PASSWORD

=== Substitute YOUR_DID & PASSWORD with your T38Fax.com SIP Credentials ===


5. Navigate to T.38 Parameters tab in the right pane and set the following:
  • Fax Transporting Protocol: T.38 only
  • Maximum Bit Rate: 14400
  • Media Passthrough Timeout Inbound: 1000
  • Media Passthrough Timeout Outbound: 15000
  • Media Renegotiate Delay Inbound: 1000
  • Media Renegotiate Delay Outbound: -1
  • T30 Fast Notify: No
  • UDPTL Redundancy Depth Control: 5
  • UDPTL Redundancy Depth Image: 2

6. Exit the Brooktrout Configuration Tool saving your changes.



Afterwards start the GFI FaxMaker service.

More details on how to configure the Dialogic SR140 can be found at the URL below:https://www.dialogic.com/webhelp/Brooktrout/SDK65/WindowsEndUserGuide.pdfYou'll want to focus on the "Configuring SIP Call Control with a Proxy Server" area of the guide to configure "Dynamic routing by a Proxy server" with your T38Fax.com account.

NOTE: SIP Registrar Setup is required with your T38Fax.com account credentials.

ALSO NOTE: Our service requires that the SIP FROM: header be received in the following format:



From: <sip:12155551212@sip.t38fax.com>



The following registry entry should be added on the GFI FaxMaker server under HKLM\Software\GFI Fax & Voice\Faxmaker\config:  

  • Type: String value
  • Name: AppendDomainToClip
  • Value: sip.t38fax.com