Fax Voip is a Windows based software that provides a full-featured SIP/H.323 softphone for Voice over IP (VoIP) calling, and also provides full functionality for sending & receiving facsimile transmissions via T.38 & G.711. From the perspective of your fax or voice application, it acts as a Voice/Fax modem, installing Virtual COM Ports and Virtual Fax Voip 14.4k TAPI Voice-Fax modems on your system. You can configure your Fax & Voice program to operate with both the Fax Voip COM ports or virtual modems. From the perspective of your VoIP network, it provides a fully featured SIP/H.323 client with support for faxing over VoIP trunks, both in G.711 and T.38 (and more importantly, with Error Correction Mode - ECM!)


T38fax.com has officially certified this software after completing rigorous testing, designed to push both the software and the virtual interfaces to their limits. We're pleased to report that the Fax Voip software has passed our requirements to make it to our Certified Device List. We’ve included a simple configuration guide on this page to help you get up and running. However, if you're running into trouble configuring your Fax Voip T38 Fax & Voice software, please open a ticket and one of our Engineers will assist you with your configuration as soon as possible!


If you don't have an account with us, that's ok! We offer a 30-day free trial that includes a free $25 credit to your account and one free DID to allow you to receive faxes. Click here if you'd like to signup for our Free Trial and take advantage of these awesome freebies!

Configuring Fax Voip with Your T38Fax.com SIP Trunk

This guide provides instructions to configure Fax Voip Software's T38 Fax & Voice software to utilize our T.38 optimized SIP Trunk service. More information on Fax Voip Software and their products can be found on their Website. If after reading this guide you still feel that you need assistance, please open a support ticket and one of our Engineers will be happy to assist you as soon as possible!



Configure Your SIP Account


Found under the Fax Voip Control Panel, navigate to "VOIP -> SIP -> Registrations" and add a new SIP Registration. You'll need to input the following information in that window:


Configure SIP Account for Fax Voip Software - T38Fax.com


Username (or SIP-ID): <Your T38Fax.com DID Here>

Password: <Input the Password for Your DID Here>
SIP Registrar Server: sip.t38fax.com
Transport: SIP over UDP



Click "OK" and then be sure to click "Apply" to fully apply your settings. We've included a screenshot to help you locate these options:






Configure Outgoing Call Routing



Configure Outbound Routing for Fax Voip Software - T38Fax.com



Configure Outgoing Call Route for Fax Voip Software - T38Fax.com




On the "General" page, in the "Dial on Line" area, configure the options below, a screenshot has been provided for your reference:



VOIP Protocol: SIP
Dial on SIP Server: sip.t38fax.com
Username: <Input Your T38Fax.com DID Here>
Transport: SIP over UDP




Configure T.38 Support for Fax Voip Software - T38Fax.com


Next, click over to the "Fax" tab. Under the "Fax Support" section, check off the box to enable T.38 support.





Be sure to enable T.38 support for the Outgoing Call Routing Rule you just created above, but also for the Outgoing Rule whose "From Line" = COM.*



When sending a fax using Fax Voip Virtual Printer, please choose the "T.38 Support" option in the Fax Voip Send Fax Wizard window.



Configure Incoming Call Routing

Configure Incoming Call Routing for Fax Voip Software - T38Fax.com



Finally, we need to configure inbound call routing on your Fax Voip software. Create your associated Incoming VOIP Call Routing rule, and be sure to check the box off under the "Fax" tab to enable T.38 Support.




Once you've completed these steps, you should be able to Send & Receive faxes reliably using the T.38 protocol! Should you run into any trouble, or find that this guide does not work in your particular deployment, please be sure to open a support ticket so our Engineering team can help diagnose and resolve your issue!