Common Fax Errors

The table below lists some of the most common fax error messages along with the likely reason and some troubleshooting steps for resolution!

📘

If these steps to resolve your issue do not help, SignalWire Support can investigate what went wrong with our carrier peers.

Please open a support request and include the Fax SID with the error. Per our carrier peers' requirements, these SIDs MUST be from the last 24 hours.

Error

Meaning

Reason

Troubleshooting Steps

Connection Failed

There was not receiver on the other end of the call to connect to

The destination is not confirmed to receive facsimile transactions

  • Retry
  • Contact the owner of the destination number to confirm compatibility and connectivity

Document generation error

There was an error while generating the document. This could be due to the file being deleted before sending

Internal Service Error

  • Retry
  • If the issue persists, contact SignalWire support

Failed to train with any of the compatible modems

A remote fax machine was detected, but the sending and receiving modems could not establish communication

Connectivity issues

  • Retry
  • Contact SignalWire Support

Fax transmission not established

We could not detect a remote fax machine. This could be due to there being no fax machine on the receiving end or a lack of call clarity.

Connectivity issues, Carrier issues, T.38 Incompatibility issue

  • Retry
  • Determine whether remote side was configured

Log entry lost

The call started but the log entry for the call was lost/incomplete. In practice, this is rare and may indicate a system problem.

Internal Service Error

  • Retry
  • Contact SignalWire Support

No response after sending a page

The remote fax machine did not acknowledge that it received a page of the fax. Depending on the remote machine's behavior, it may still have printed the page and any preceding pages.

Connectivity issues

  • Retry
  • Contact destination to ensure delivery

Received no response to DCS or TCF

The bulk fax service could not successfully determine the remote machine's fax capabilities

T.38 Incompatibility issue

Determine whether the remote side was configured for T.38 only. SignalWire only supports faxes sent using the T.30 protocol.

The call dropped prematurely

The call dropped due to non-fax transmission error. It is likely that the receiver hung up.

Inbound to SignalWire: The destination is a voice number or not set up to receive faxes. Outbound: The destination is a voice number, or the destination returns ringing for so long that the transmission times out before the handshake can be established.

Retry
Note: SignalWire Fax only supports the transmission of PDFs to fax-enabled destinations

The HDLC carrier did not stop in a timely manner

The fax service initiated a fax transmission with the receiver, but there was synchronization (timing) error that could not be resolved.

Likely low-quality routes

  • Retry
  • If network conditions persist, contact SignalWire Support to reach out carrier peer

Timed out waiting for initial communication

A call was established with the receiver, and the bulk fax service attempted to establish a fax session. However, there was no fax response from the receiver. This could be due to there being no fax machine on the receiving end or lack of call clarity.

No remote fax machine or poor quality routes

  • Retry
  • If network conditions persist, contact SignalWire Support to reach out to carrier peer

Unexpected DCN while waiting for DCS DIS

The remote fax machine unexpectedly sent a disconnect message when the fax service asked for the remote fax machine's fax capabilities

T.38 Incompatibility issue

Determine whether the remote side was configured for T.38 only. The protocol is not designed to recover from these situations; all that can be done is fail.

Disconnected after permitted retries

The fax service attempted to send the same message multiple times unsuccessfully. This may be due to a call clarity issue.

Poor network conditions

  • Retry
  • If network conditions persist, contact SignalWire Support to reach out to carrier peer

Far end cannot receive at the resolution of the image

The remote fax machine does not support receiving faxes sent by our service

Quality is too high

Try lowering quality (Resolution is known as "quality" in Programmable Fax).

Received a DCN from remote after sending a page

The remote fax machine responded with a disconnect message after a page was sent successfully. Depending on the remote machine's behavior, it may have still printed the sent page and any preceding pages.

Poor network conditions

  • Retry
  • If network conditions persist, contact SignalWire Support to reach out to carrier peer

Unexpected message received

The fax service received a message that it did not expect given the current context

Protocol failure

Determine whether the expected number of pages matches the number of successfully transmitted pages. Failure may have been in tearing down the call.

Unexpected DCM after EOM or MPS sequence

The remote fax machine disconnected unexpectedly after receiving a page of a multi-page fax. Depending on the remote machine's behavior, it may have still printed the sent pages and any preceding pages.

Poor network conditions

  • Retry
  • If network conditions persist, contact SignalWire Support to reach out to carrier peer

Document loading error

The fax service attempted to generate the message to send but a document was missing

Internal Service Error

  • Retry
  • If the issue persists, contact SignalWire support

Invalid ECM response received from receiver

The fax service received an invalid error correction message from the remote fax machine

T.38 Incompatibility issue

  • Retry
  • If failures only occur with one number, there's a chance that the remote fax machine is incompatible with our infrastructure. SignalWire only supports faxes sent using the T.30 protocol.

Did this page help you?