Troubleshooting - Portal Fax

Updated at August 26th, 2026

Prerequisites:

  • A Portal Fax Account
  • Access to the portal
 

This article covers how to troubleshoot some more common portal fax troubles.

Not Receiving Fax Emails

Please ensure that your portal account has voicemail enabled and email alerts selected. If either feature is disabled, you will not receive faxes to your email. However, they will appear in the portal messages area.

Can Receive but Cannot Send Faxes

If your Portal Fax account is receiving faxes successfully but outbound faxes are failing, work through the following checks in order.

1. Check your monthly page limit

Portal Fax supports up to 200 pages per month. If the limit has been reached, outbound faxes will fail silently or queue without sending. Log in to the portal, navigate to your fax user settings, and confirm the current page usage for the billing period. If the limit has been reached, outbound sending will resume at the start of the next billing cycle.

2. Confirm the file format and size

Portal Fax supports the following file types: PDF, DOC, DOCX, JPG, TIF, and PNG. Files must not exceed 20MB and 200 pages per fax. If the file is in an unsupported format or exceeds these limits, the fax will fail to send without a clear error message. Convert the file to PDF and retry.

3. Check the destination number

Confirm the fax number is correct including the area code, and that the destination fax machine is on and ready to receive. Try calling the number from a regular phone to confirm it is active before resending.

4. Check for error messages in the fax history

Navigate to your fax user settings in the portal and review the outbound fax history. If an error code is shown, refer to the error reference below.

Error Reference for Portal Fax Send Failures

The following errors may appear in your portal fax history for outbound faxes. These are based on the Phaxio error taxonomy used by the Portal Fax platform.

Error What It Means What To Do
Unexpected DCN while waiting for DCS or DIS The remote fax machine sent a disconnect signal during the initial handshake before fax negotiation completed. This is typically a compatibility issue with the receiving machine. Ask the recipient to check their fax machine. Request they send a test fax to a different number to confirm it is working correctly. Try resending at a different time.
No response after sending a page The remote machine stopped responding after receiving part of the fax. Retry. If it persists, ask the recipient to check their fax machine's paper and ink status.
Failed to train with any compatible modems The two fax machines could not agree on a compatible transmission speed or protocol. Retry. If persistent, ask whether the recipient's fax machine supports T.38 or is on an analogue landline.
Far end cannot receive at the size of image The receiving fax machine does not support the document size being sent (e.g. legal vs letter). Reformat the document to standard letter size (8.5 x 11 inches) and retry.
The remote fax machine hung up before receiving fax The receiving machine answered but immediately disconnected. May indicate the machine is busy, out of paper, or incompatible. Contact the recipient to confirm their machine is ready to receive and retry.
No fax tone detected The number answered but is not a fax line, or the fax machine is not in receive mode. Confirm the destination number is a fax line and the machine is set to auto-receive mode.
Incomplete transmission The fax started sending but did not complete. Often caused by network interruption or remote machine disconnection. Retry. If persistent, try sending a shorter document to determine whether the issue is file-length related.

Note: Portal Fax retries automatically before marking a fax as failed. If you do not see an error in your portal history, the fax may still be in queue. Allow a few minutes before checking the status.

Contact Support

If you have any other issues, please contact support, and be sure to provide any identifying information. 

  • What are the intended phone numbers for sending and receiving?
  • What approximate time was the Fax attempted? 
  • What happened when the fax was sent? Any Error Messages?

 

Error Messages

When your receive a callback from Portal fax notifying you of a failure, it will contain two values that can help you understand what went wrong: an error_code and an error_type.

The error_type will give you a general idea of why the operation failed, whereas the error_code describes the issue in more detail. Below we list the error_codes for the API, segmented by their corresponding error_type.

The 5 error types:

Document Conversion Error

documentConversionErrors usually occur when there is a problem with one of the files you posted.

id message
4 There was a problem in converting and merging files to the output file format. Contact support.
54 Could not access the url you provided.
55 The string_data URL you provided is invalid
57 There was a problem storing the file you provided.
69 There was a problem in converting and merging files to the output file format.
122 User simulated Document Conversion Error
128 Could not determine mimetype for file.
129 Mimetype not supported.
130 Mimetype not supported: application/xml
133 Failed to normalize PDF document

Line Error

There was a problem with the phone line. The call could not be placed.

id message
11 The call dropped prematurely
15 Congestion
16 Ring Timeout
17 Busy
19 Immediate Hangup
30 No answer from the fax machine.
32 Incompatible destination
34 Phone number not operational
43 Problem establishing connection
49 The Receiving Phone Number Is Not Operational
50 Call rejected
52 No route available
73 Number changed
87 No answer from the fax machine
88 Network Error
100 Problem with remote carrier
110 Network error
112 No answer
115 The phone number has been changed
121 User requested simulated lineError

Fax Error

A problem occured during the fax communication process.

id message
6 There was an error communicating with the far side.
7 Far end cannot receive at the size of image
8 No response after sending a page
10 Disconnected after permitted retries
12 Received no response to DCS or TCF
13 Timed out waiting for the first message
14 Timed out waiting for initial communication
18 Unexpected message received
20 The HDLC carrier did not stop in a timely manner
21 Received a DCN from remote after sending a page
22 Received bad response to DCS or training
25 Far end cannot receive at the resolution of the image
26 The remote fax machine failed to respond
28 Failed to train with any of the compatible modems
29 Invalid response after sending a page
31 Fax machine incompatibility
38 The remote fax machine hung up before receiving fax
40 Telephony error
41 Unexpected DCN while waiting for DCS or DIS
44 Telephony Error
46 Insufficient funds to send fax and not able to auto recharge: There was a problem charging your credit card. Please check your payment information and try again.
48 No answer (The Receiving Machine May Be Out Of Paper)
53 Unexpected DCN after EOM or MPS sequence
60 Transmission error after page break
63 Fax protocol error
68 Far end is not compatible
75 Manually canceled by user
76 Canceled automatically because timeout exceeded
77 Timed out waiting for receiver ready (ECM mode)
79 Can't cancel the fax, it's already complete!
80 Received a DCN while waiting for a DIS
82 There was an error communicating with the far side
84 Unexpected command after page received
113 The file for this fax has been deleted or is not accessible.
117 No pages received
119 User requested simulated faxError
131 Incomplete transmission
132 No fax tone detected

Fatal Error

Something went wrong internally on our systems. This should occur very infrequently.

id message
9 Could not send the file to the fax server for spooling
23 There was a problem in the final stages of sending your fax. Contact support.
24 Error 500 - There was a problem in processing your request
126 User requested simulated fatalError

General Error

Similar to fatalError but higher priority. As soon as one of these occurs, rest assured that we’re looking into it immediately and will follow up with what went wrong.

id message
3 General error. Contact support.
5 Insufficient funds to send fax and not able to auto recharge.
86 Insufficient funds to send fax and not able to auto recharge: Cannot autorecharge. There have been 4 or more failed billing attempts for this card.
120 User requested generalError
125 Insufficient funds to send fax and not able to auto recharge: Cannot autorecharge at this time. We've attempted to charge repeatedly in the past 2 hours.
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