FAX Support - Troubleshooting Distorted Images When Faxing

Table of Contents

If faxing over an extension, what Codecs are used on those extensions?

1. Go to Setup > Manage > click modify pencil > Phone Settings tab > Advanced Phone Options > Codec Settings: click on icon under Actions to enable or disable a codec. You can also reorder the codecs to prioritize.

What are the fax settings on the extensions?

1. Login to extension, go to Voicemail/Fax > Fax Options > Sending/Receiving > Advanced Options

2. Try setting the Min Transfer Rate for Fax Transmissions to 9600

Is Error Correction Mode for G711 Faxes enabled or disabled on the extension?

1. Login to the extension.

2. Go to Voicemail/Fax > Fax Options > Sending/Receiving > Disable EMC for G711 Fax Sessions > If Yes, try setting it to No

If faxing over a PRI connection, Is Relax DTMF Recognition enabled in the PRI Channel Groups?

1. Go to Setup > Channel Groups > click on modify pencil for the PRI T1 B Channel

2. Click the Hide Advanced Group Options button and select Show Advanced Group Options.

3. Set Relax DTMF Recognition to Yes

Is Fax Detection set to both on the PRI Channel Group?

In order to receive incoming faxes over PRI, you must set the fax detection to Both: 

1. Go to Setup > Channel Groups > Click the Modify button for your PRI T1 B Channel to access the PRI T1 B Channel Settings.

2. Click the Hide Advanced Group Options button and select Show Advanced Group Options.

3. Scroll down to the bottom of the Advanced Group Options and set the Fax Detection to Both

If these changes still result in distorted images, verify that the source file is not corrupted or an unsupported image format. Using a PDF should work, try using a different PDF for testing.

Run an Asterisk Command Line Interface debug (ACLI) for Fax Messages and send a test fax.