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8x8 Support

Troubleshooting Issues with Fax Devices


Common Physical Fax Symptoms

  1. Unable to send or receive.
  2. Able to receive, but not able to send.
  3. Failure on first send attempt.
  4. Fax cut off.
  5. Cannot send to specific numbers.

Questions to Consider

  1. How long has the issue occurred?
  2. Does the failure occur on outbound, inbound, or both?
  3. Does it happen when dialing to a specific number or area code?

Applies To

Physical fax endpoints


Send/Receive Problems

Can Neither Send Nor Receive

  1. Check fax speed and baud rate on fax machine.
  2. Log in to the web GUI ATA device and ensure that the Preferred Codec is set to G.711 and T.38 is enabled.
  3. Check physical connections to and from the adapter.
    • Make sure the telephone cable is going from Line 1 on the adapter to Line 1 on the fax machine (unless you have a second port activation on your fax extensions).
    • Ensure the adapter is plugged into a valid Internet source.
  4. Check adapter-specific network settings.
  5. Attempt to set a static IP on the adapter.
  6. Make a test call to another fax number. You should hear fax tones. If it rings through as disconnected, proceed.

First Send Attempt Fails

  • Attempt to resend the fax.

Fax Cut Off

First, check that all settings are properly configured as outlined above.

If the problem continues after proper configuration, and you are currently using an SPA 122 VoIP adapter, try swapping it for a BPA430 adapter.

Cannot Send to Specific Numbers

If you cannot send faxes to specific numbers, please create a case with 8x8 Technical Support.


To ensure optimal fax machine performance, there are several settings that must be configured.

  • On the fax machine, please check the following settings:
    • Fax Speed or Baud Rate should be lowered to 9600bps.
    • Error Correction Mode (ECM) should be disabled.
    • Resolution should be Standard (not Fine, Ultrafine, Photo, etc.).
    • Overseas (International) Mode set to ON.
    • Set to Fax-Only mode.
  • Call Waiting must be disabled for the fax extension.
  • If you are using an MGCP BPA430 or similar adapter, prioritize port 15044 on the network.
  • If you are using a Cisco (Linksys) SPA 122 or 2102 adapter

Additional Information

Fax Servers

While fax servers are not supported, they may work with an adapter. In instances where issues arise with an ATA connected to a fax server, 8x8 support will troubleshoot the adapter. To isolate correctly if the issue is the fax server or adapter, it may be necessary to connect the ATA to a fax machine, or an analog phone. If the issue is determined to be the fax server, 8x8 cannot assist in troubleshooting after confirming the ATA is working correctly.

Fax Machines

8x8 Support will assist with the general settings listed above on fax machines, however, 8x8 cannot troubleshoot the fax machine itself. 

Messages related to a full mailbox must be verified in the inbox of the receiving email or on the fax device itself, as there is no fax cap set by 8x8 on the amount it's possible to receive. 

Fax Tone

The ATA adapter only provides a dial tone. In instances where fax tone is not being provided the adapter will be troubleshot and settings verified, but ultimately fax tone is provided by the machine itself





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