It is possible to route a fax to a SIP ATA device just like any other call in the WebCentrex platform.    Faxes routed this way will use either T.38 or G711 for the fax transmission.  You are able to control the transmission mode by adjusting the codec preferences on the SIP device.  


ParagonVoIP supports faxing with a SIP ATA on a best efforts basis only!

Because fax machines rely on the analog representation of a digital signal (what you hear as a "fax tone") they are very sensitive to deviations in the fax data transmission. In practice this means that faxes are often interrupted by jitter and latency in the last mile (the portion of the call path between the switch and the end-user's fax machine). This level of unreliability causes most VoIP service providers to avoid deploying faxes using SIP ATAs. 

We strongly recommend that cusotmers deploy faxing using the ParagonVoIP Instant Fax ATA or Instant Fax Portal services.


Steps to Configure Analog ATA for Faxing  

Create Fax User

Create a PBX User as normal.  Note that you should not assign a Fax device to a User that also has another SIP device configured.

Add ATA Device to Fax User

  • Navigate to the phone tab of the newly installed user.

  • Click add phone
  • Select any of the supported ATA devices.  If your ATA is not available in the Model field please request further assistance

by opening a ticket with support.

  • Fill in all fields and click Add

Route DID to Fax User

From the DID Inventory page, choose a DID and route it to the Fax User that you previously created.


Note that the Fax Treatment option in the DID Inventory page causes the system to ignore any voicemail or forwarding rules.  This is desirable so that fax calls are not routed to destinations that may not have a fax machine attached.   


Reboot ATA device.