1) Fax - Errors contained in the Webhook Payload:
These error details will be included in the failure_reason field contained in the Fax API Webhook event payloads. For tutorials and other details on the API Requests and Webhook payload formats, please refer to this Documentation.
Outbound Programmable Fax Errors
Error | Description |
file_size_limit_exceeded | Error from Telnyx programmable FAX Application indicating the .pdf file provided is greater in size than the prescribed limits. (i.e. bigger than 50MB) |
page_count_limit_exceeded | Error from Telnyx programmable FAX Application indicating the .pdf file provided is containing more number pages than the prescribed limits. (i.e. more than 350 Pages) |
fax_initial_communication_timeout | This may indicate that the call did not connect to a valid fax machine/the destination is not sending fax tones. |
fax_signaling_error | Error from Telnyx Telephony Engine. Includes scenarios such as no response after sending a page, receiving a bad response to a DCS fax message, or training. |
file_download_failed | The non-telephony service responsible for downloading the customer's PDF prior to initiating the fax was unable to download the file. Please ensure that there are no redirect responses (3XX HTTP); only 2XX HTTP responses will ensure we download your file and process it. |
file_format_invalid | The customer file format is not PDF or is an invalid PDF. |
receiver_call_dropped | Error from Telnyx Telephony Engine. The call dropped prematurely. |
receiver_communication_error | Error from Telnyx Telephony Engine. It may indicate a general call failure or a telephony routing error. |
receiver_decline | Error from Telnyx Telephony Engine. The destination declined the call attempt. |
receiver_invalid_number_format | Error from Telnyx Telephony Engine. The destination number is not in a valid +E.164 format. |
receiver_no_response | Error from Telnyx Telephony Engine. This cause is used when a called party does not respond to a call establishment message with either an alerting or connect indication within the prescribed period of time allocated. |
receiver_recovery_on_timer_expire | Error from Telnyx Telephony Engine. Remote party sends a SIP 408 for an expired/timed-out call or an issue with the downstream carrier partner. |
receiver_unallocated_number | Error from Telnyx Telephony Engine. This cause indicates that the called party cannot be reached because, although the called party number is in a valid format, it is not currently allocated (assigned). |
service_unavailable | Internal Telnyx error. A call to another service, such as to initiate the outbound call or to retrieve the PDF for sending, failed. Could also be due to a non-typical media conversion failure. |
success | Telnyx to investigate this further. |
NOTE: Retries for outbound faxes, which may result in an error must be configured on the client application; Telnyx does not automatically retry faxes with errors.
Inbound Programmable Fax Errors
Error | Description |
carrier_lost | The connection to the carrier dropped while receiving the fax |
fax_signaling_error | Error from Telnyx Telephony Engine. Similar to outbound error, but in reverse. Includes scenarios such as no further data after receiving a page, bad data sent from the sender etc. |
received | Telnyx to investigate this further. |
sender_call_dropped | Error from Telnyx Telephony Engine. The call dropped prematurely. |
sender_canceled | Error from Telnyx Telephony Engine. The sender canceled the call prematurely or before the data had completed transmitting. |
sender_communication_error | Error from Telnyx Telephony Engine. Can include a general call failure or a telephony routing error on the sender side. |
Other Webhook Fax Errors Include:
account_disabledconnection_channel_limit_exceededdestination_invaliddestination_not_in_countries_whitelistdestination_not_in_service_plandestination_unreachableinvalid_ecm_response_from_receiverno_outbound_profileoutbound_profile_channel_limit_exceededoutbound_profile_daily_spend_limit_exceededreceiver_incompatible_destinationreceiver_no_answeruser_busyuser_channel_limit_exceededfax_initial_communication_timeout
2) Fax - Errors in the Fax API CDR
These error codes and messages are contained in the last 2 columns in the CSV file generated by the Telnyx Portal Reporting Section, specifically, when selecting "Report Type": "Fax API".
Result Code | Message |
0 | OK |
2 | Timed out waiting for initial communication |
3 | Timed out waiting for the first message |
5 | The HDLC carrier did not stop in a timely manner |
6 | Failed to train with any of the compatible modems |
13 | Unexpected message received |
14 | Received bad response to DCS or training |
15 | Received a DCN from remote after sending a page |
17 | Received a DCN while waiting for a DIS |
20 | Received no response to DCS or TCF |
23 | Invalid ECM response received from transmitter |
31 | Timer T2 expired while waiting for fax page |
32 | Timer T2 expired while waiting for next fax page |
48 | Disconnected after permitted retries |
49 | The call dropped prematurely |