Recommended ATA Fax and Audio settings

This article explains how to adjust settings on ATA device that have proven to help with faxing or audio issue.   

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If you are experiencing failed faxes or audio issues with an ATA device the following adjustments may help.

You will need to login to the ATA's web GUI as the administrator.  After logging in, browse to the advanced settings tab and verify that under Voice → Regional " Ring and Call Waiting Tone Spec" is set as follows:

  • Set 'Ring Waveform' to Trapezoid
  • Set 'Ring Voltage' to 85
  • Set 'Synchronized Ring' to no
  • Set 'Ring Frequency' to 20
  • Set 'CWT Frequency' to 440@-10

After making those changes, you will need to adjust settings on the 2 line ports.

Navigate to the Voice section of the PAP2's → Line 1 (or line 2) and ensure the grouped settings below have been input based on the intended use of the line (fax or audio).

Fax Settings
Audio Settings

Note: Echo Cancellation can improve or degrade quality in both scenarios and may require some testing. Test with it disabled first.


Fax settings:

Under the section labelled Network Settings:

  • Set 'Network Jitter Level' to very high
  • Set 'Jitter Buffer Adjustment' to no

Then under Supplementary Service Subscription:

  • Set 'Call Waiting Serv' to no
  • Set 'Three Way Call Serv' to no

And finally, under the Audio Configuration section make the following adjustments:

  • Set 'FAX Codec Symmetric' to yes
  • Set 'FAX Passthru Method' to ReINVIITE
  • Set 'FAX Process NSE' to yes
  • Set 'FAX disable ECAN' to yes
  • Set 'Use Pref Codec Only' to yes
  • Set 'Silence Supp Enabled' to no
  • Set 'Silence Threshold' to medium
  • Set 'Echo Canc Enabled' to no 
  • Set 'FAX Passthru codec' to G711u
  • Set 'FAX Tone Detect Mode' to callee only

Audio/Phone settings:

  • Set 'Use Pref Codec only' to yes
  • Set 'Silence Supp Enabled' to no
  • Set 'Silence Threshold' to low
  • Set 'Echo Canc Enabled' to no 

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