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Rewrite: Common Fax Errors #408

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217 changes: 114 additions & 103 deletions fern/products/platform/pages/calling/fax/common-fax-errors.mdx
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Expand Up @@ -3,211 +3,222 @@ id: ca36587f-5d99-47de-9f43-ba779e5146eb
slug: /fax/common-errors
title: Common fax errors
description: Our guide to understanding and troubleshooting the most common fax error messages.
max-toc-depth: 3
x-custom:
ported_from_readme: true
tags:
- product:fax
---

The table below lists some of the most common fax error messages along with the likely reason and some troubleshooting steps for resolution.
This page lists the most common fax error messages along with the likely reason and troubleshooting steps for resolution.
If these steps don't resolve your issue, open a support request and include the Fax SID with the error.
<Warning>
**Per our carrier peers' requirements, these SIDs MUST be from the last 24 hours**. SIDs older than 24 hours cannot be investigated.
</Warning>

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._

## List of common errors
## Common errors

### Connection Failed

**Meaning:** There was not receiver on the other end of the call to connect to.
**Meaning:** There was no receiver on the other end of the call to connect to.

**Reason:** The destination is not confirmed to receive facsimile transactions.

**Troubleshooting Steps:**
**Troubleshooting steps:**

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

### Disconnected after permitted retries

- Retry
- Contact the owner of the destination number to confirm compatibility and connectivity
**Meaning:** The fax service attempted to send the same message multiple times unsuccessfully. This may be due to a call clarity issue.

**Reason:** Poor network conditions.

**Troubleshooting steps:**

- Retry.
- If network conditions persist, contact SignalWire Support to reach out to our carrier peer.

### Document generation error

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

**Reason:** Internal Service Error.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If the issue persists, contact SignalWire support
- Retry.
- If the issue persists, contact SignalWire support.

### Failed to train with any of the compatible modems
### Document loading error

**Meaning:** A remote fax machine was detected, but the sending and receiving modems could not establish communication.
**Meaning:** The fax service attempted to generate the message to send but a document was missing.

**Reason:** Connectivity issues.
**Reason:** Internal Service Error.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If the issue persists, contact SignalWire support
- Retry.
- If the issue persists, contact SignalWire support.

### Fax transmission not established
### Failed to train with any of the compatible modems

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

**Reason:** Connectivity issues, Carrier issues, T.38 Incompatibility issue.
**Reason:** Connectivity issues.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- Determine whether remote side was configured
- Retry.
- If the issue persists, contact SignalWire support.

### Log entry lost
### Far end cannot receive at the resolution of the image

**Meaning:** The call started but the log entry for the call was lost/incomplete. In practice, this is rare and may indicate a system problem.
**Meaning:** The remote fax machine does not support receiving faxes sent by our service.

**Reason:** Internal Service Error
**Reason:** Quality is too high.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If the issue persists, contact SignalWire support
- Try lowering quality (resolution is known as "quality" in Programmable Fax).

### No response after sending a page
### Fax transmission not established

**Meaning:** 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.
**Meaning:** 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.

**Reason:** Connectivity issues
**Reason:** Connectivity issues, carrier issues, T.38 incompatibility issue.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- Contact destination to ensure delivery
- Retry.
- Determine whether the remote side was configured.

### Received no response to DCS or TCF
### Invalid ECM response received from receiver

**Meaning:** The bulk fax service could not successfully determine the remote machine's fax capabilities
**Meaning:** The "Invalid ECM (Error Correction Mode) response received from receiver" error indicates that there's an issue with the error correction process, where the receiving fax machine's response to a request for error correction didn't match expected parameters or was not understood by the sending machine.

**Reason:** Network or incompatibility issues.

**Troubleshooting Steps:**
- Retry
- Determine whether the remote side was configured for supported fax protocols (T.38/T.30).
- Ensure the remote side's network is stable.
**Troubleshooting steps:**

- Retry.
- If failures only occur with one number, there's a chance that the remote fax machine is incompatible with our infrastructure.

### Log entry lost

### The call dropped prematurely
**Meaning:** The call started but the log entry for the call was lost or incomplete. In practice, this is rare and may indicate a system problem.

**Meaning:** The call dropped due to non-fax transmission error. It is likely that the receiver hung up.
**Reason:** Internal Service Error.

**Reason:** 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.
**Troubleshooting steps:**

**Troubleshooting Steps:** Retry. _Note: SignalWire Fax only supports the transmission of PDFs to fax-enabled destinations._
- Retry.
- If the issue persists, contact SignalWire support.

### The HDLC carrier did not stop in a timely manner
### No response after sending a page

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

**Reason:** Likely low-quality routes.
**Reason:** Connectivity issues.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If network conditions persist, contact SignalWire Support to reach out carrier peer
- Retry.
- Contact destination to ensure delivery.

### Timed out waiting for initial communication
### Received a DCN from remote after sending a page

**Meaning:** 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.
**Meaning:** 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.

**Reason:** No remote fax machine or poor quality routes.
**Reason:** Poor network conditions.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If network conditions persist, contact SignalWire Support to reach out to carrier peer
- Retry.
- If network conditions persist, contact SignalWire Support to reach out to our carrier peer.

### Unexpected DCN while waiting for DCS DIS
### Received no response to DCS or TCF

**Meaning:** "Unexpected DCN (Disconnect) while waiting for DCS (Digital Command Signal) or DIS (Digital Identification Signal)" implies that the fax machine received
a disconnect signal unexpectedly during the initial negotiation phase, before the communication
parameters were fully agreed upon.
**Meaning:** The bulk fax service could not successfully determine the remote machine's fax capabilities.

**Reason:** Network or incompatibility issues.

**Troubleshooting Steps:**
- Retry
**Troubleshooting steps:**

- Retry.
- Determine whether the remote side was configured for supported fax protocols (T.38/T.30).
- Ensure the remote side's network is stable.
- If failures only occur with one number, there's a chance that the remote fax machine is incompatible with our infrastructure.

### Disconnected after permitted retries

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

**Reason:** Poor network conditions.
### The call dropped prematurely

**Troubleshooting Steps:**
**Meaning:** The call dropped due to a non-fax transmission error. It is likely that the receiver hung up.

- Retry
- If network conditions persist, contact SignalWire Support to reach out to carrier peer
**Reason:** 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.

### Far end cannot receive at the resolution of the image
**Troubleshooting steps:**

**Meaning:** The remote fax machine does not support receiving faxes sent by our service.
- Retry.

**Reason:** Quality is too high.
**Note:** SignalWire Fax only supports the transmission of PDFs to fax-enabled destinations.

**Troubleshooting Steps:** Try lowering quality (Resolution is known as "quality" in Programmable Fax).
### The HDLC carrier did not stop in a timely manner

### Received a DCN from remote after sending a page
**Meaning:** The fax service initiated a fax transmission with the receiver, but there was a synchronization (timing) error that could not be resolved.

**Meaning:** 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.
**Reason:** Likely low-quality routes.

**Reason:** Poor network conditions.
**Troubleshooting steps:**

**Troubleshooting Steps:**
- Retry.
- If network conditions persist, contact SignalWire Support to reach out to our carrier peer.

- Retry
- If network conditions persist, contact SignalWire Support to reach out to carrier peer
### Timed out waiting for initial communication

### Unexpected message received
**Meaning:** 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.

**Meaning:** The fax service received a message that it did not expect given the current context.
**Reason:** No remote fax machine or poor quality routes.

**Reason:** Protocol failure.
**Troubleshooting steps:**

**Troubleshooting Steps:** Determine whether the expected number of pages matches the number of successfully transmitted pages. Failure may have been in tearing down the call.
- Retry.
- If network conditions persist, contact SignalWire Support to reach out to our carrier peer.

### Unexpected DCM after EOM or MPS sequence

**Meaning:** 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.

**Reason:** Poor network conditions.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If network conditions persist, contact SignalWire Support to reach out to carrier peer
- Retry.
- If network conditions persist, contact SignalWire Support to reach out to our carrier peer.

### Document loading error
### Unexpected DCN while waiting for DCS DIS

**Meaning:** The fax service attempted to generate the message to send but a document was missing.
**Meaning:** "Unexpected DCN (Disconnect) while waiting for DCS (Digital Command Signal) or DIS (Digital Identification Signal)" implies that the fax machine received a disconnect signal unexpectedly during the initial negotiation phase, before the communication parameters were fully agreed upon.

**Reason:** Internal Service Error
**Reason:** Network or incompatibility issues.

**Troubleshooting Steps:**
**Troubleshooting steps:**

- Retry
- If the issue persists, contact SignalWire support
- Retry.
- Determine whether the remote side was configured for supported fax protocols (T.38/T.30).
- Ensure the remote side's network is stable.
- If failures only occur with one number, there's a chance that the remote fax machine is incompatible with our infrastructure.

### Invalid ECM response received from receiver
### Unexpected message received

**Meaning:** The fax service received a message that it did not expect given the current context.

**Meaning:** The "Invalid ECM (Error Correction Mode) response received from receiver" error indicates that there's an issue
with the error correction process, where the receiving fax machine's response to a request for error correction didn't
match expected parameters or was not understood by the sending machine.
**Reason:** Protocol failure.

**Reason:** Network or incompatibility issues.
**Troubleshooting steps:**

**Troubleshooting Steps:**
- Determine whether the expected number of pages matches the number of successfully transmitted pages. Failure may have been in tearing down the call.

- Retry
- If failures only occur with one number, there's a chance that the remote fax machine is incompatible with our infrastructure.
## Still having issues?

If you've worked through the troubleshooting steps above and the error persists, [open a ticket with SignalWire Support](https://support.signalwire.com) and include the Fax SID from the last 24 hours so our team can investigate with our carrier peers.
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