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Asterisk AMI fax session is missing, stale or statistics do not match

Find the first divergence across module support, completed active-session inventory, session timing, conditional detail fields, manager delivery, process-counter scope and terminal fax evidence.

Reviewed 2026-10-26Current branch-23-generated Asterisk FAXSession, FAXSessions and FAXStats actions and response events, FAXStatus, ReceiveFAX, SendFAX, FAXOPT, AMI v2 and network-security documentation were reviewed October 26, 2026; installed Asterisk version, res_fax and technology module availability, manager permissions and filters, session timing, counter lifetime, channel and dialplan ownership, storage, notification and FreePBX behavior remain deployment-specific; no PBX, FreePBX system, module, manager account, credential, fax session, channel, TIFF/F file, notification, packet, media stream or document delivery was inspected or testedAdvancedDocumentation based · not lab tested

Freeze one node, transaction and contradiction

Record node, build, process start context, loaded fax modules, manager identity, action, ActionID, response, every matching event, list completion, session number, channel identifiers, dialplan application, filename, terminal variables and the first contradictory timestamp.

Classify the symptom as unknown action, denied action, incomplete list, empty completed list, vanished session, detail-action failure, conditional field absent, counter mismatch, missing progress event or disagreement with a terminal application result. Do not merge several sessions or restarts into one incident.

Prove module and action support before interpreting data

Confirm res_fax and the intended fax technology module are loaded for the exact responding process, and inventory the manager commands visible to the authenticated identity. FAXSession can fail when the technology used by that session has no handler even though fax transmission itself exists.

If the action is absent or denied, repair module availability or authorization first. Do not infer session failure from an unsupported observation surface.

Repeat a bounded completed active-session list

Run FAXSessions with a fresh ActionID, retain every FAXSessionsEntry, wait for the matching FAXSessionsComplete, and compare Total with the retained row count. Capture while the target fax is demonstrably in progress and repeat at a documented interval.

A fax can finish between the dialplan, progress-event and inventory samples. An empty completed list after completion is not stale; a list without its completion event is not a trustworthy zero.

Resolve session identity and conditional detail fields

Use the numerical SessionNumber from the list or an established FAXOPT(sessionid) join for FAXSession. Keep it separate from channel name, Uniqueid, Linkedid and filename. Compare operation and state before requiring optional fields: technology, operation and lifecycle state determine which details can appear.

Treat changing page counts and state as snapshots. A filename or session match does not prove that the TIFF/F artifact is readable or that notification and delivery completed.

Reconcile statistics inside one process lifetime

Sample FAXStats before and after one authorized test, retaining CurrentSessions, ReservedSessions, TransmitAttempts, ReceiveAttempts, CompletedFAXes and FailedFAXes with process identity and timestamps. Compare deltas only when no unrelated fax traffic or restart invalidates attribution.

Counters and an active-session list observe different scopes and moments. A session can leave the list and increment a terminal counter; cumulative counts can also include other traffic. Use terminal FAXSTATUS, FAXERROR, pages, rate, resolution and mode for the individual dialplan result.

Repair the first owner and verify the full boundary

Correct only the demonstrated owner: module support, AMI authorization, event filtering, collector list completion, sampling window, identifier join, dialplan result handling, TIFF/F storage or notification pipeline. Re-run one bounded transaction and retain both runtime and terminal observations.

Verify file readability and downstream delivery separately when required, then remove test artifacts under the owning system policy. No PBX, module, manager session, fax session, TIFF/F file, notification, packet, media stream or document delivery was inspected or tested.

Sources & applicability

Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.

Examples require adaptation to your topology. No live PBX or hardware testing is claimed.

Continue your research

Guide · Current branch-23-generated Asterisk FAXSession, FAXSessions and FAXStats actions and response events, FAXStatus, ReceiveFAX, SendFAX, FAXOPT, AMI v2 and network-security documentation were reviewed October 26, 2026; installed Asterisk version, res_fax and technology module availability, manager permissions and filters, session timing, counter lifetime, channel and dialplan ownership, storage, notification and FreePBX behavior remain deployment-specific; no PBX, FreePBX system, module, manager account, credential, fax session, channel, TIFF/F file, notification, packet, media stream or document delivery was inspected or tested

Asterisk AMI fax session inventory and statistics evidence

Use FAXSessions, FAXSession and FAXStats as bounded runtime observations while keeping progress events, terminal application results, negotiated mode and delivered-document evidence separate.

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Troubleshooting · Asterisk 22 FAXOPT, ReceiveFAX and SendFAX documentation plus branch 22 res_fax configuration and implementation reviewed October 13, 2026; the installed Asterisk version, res_fax module, technology resource, configuration, channel, TIFF/F file, signaling, T.38 negotiation, audio path, session result, storage and delivery remain deployment specific, and no host, module, file, channel, packet, fax session or document was inspected or tested

Asterisk ReceiveFAX or SendFAX fails or uses the wrong mode

Trace one fax from the exact channel and loaded res_fax stack through FAXOPT inputs, file access, audio or T.38 negotiation, application result and downstream artifact handling.

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Guide · Analog interface and carrier behavior vary by device, region and firmware

Fax-over-VoIP troubleshooting by failure stage

Distinguish call setup, fax negotiation, page transfer and completion failures.

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Troubleshooting · FreePBX 17 / Debian 12 editorial baseline; Sangoma Fax Pro documentation and product boundary, FreePBX Fax Configuration release/17.0 source, and current Asterisk ReceiveFAX and FAXOPT documentation reviewed October 11, 2026; installed module, license, generated dialplan, storage, mail transport and live behavior remain authoritative, and no PBX, license, DID, route, recipient, fax session, file, conversion, message, mailbox, UCP item, quota, document or remote machine was inspected or tested

FreePBX received the fax but email or the UCP copy is missing

Start with one completed ReceiveFAX session, then trace recipient mapping, attachment conversion, local storage, quota, UCP visibility and email delivery.

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Troubleshooting · Current Asterisk branch-23-generated Events, Filter, WaitEvent, Login and Ping action references, matching branch-22 Events, Filter and WaitEvent references, the official AMI event-filtering guide and Manager TCP/IP API reviewed October 16, 2026; installed branch, manager user permissions, login mask, static and dynamic filters, connection type, event queue, client parser, reconnect behavior, action concurrency, downstream storage and call activity remain deployment specific; no PBX, AMI session, manager user, permission, configuration file, socket, HTTP session, event queue, channel, bridge, packet, media stream or live call was inspected or tested

Asterisk AMI events are missing, filtered, delayed or duplicated

Locate the first divergence among manager permissions, the per-session event mask, configured and dynamic filters, HTTP WaitEvent queueing, TCP reads, reconnects, parsing and downstream deduplication.

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Guide · Wireshark 4.x / current upstream tool documentation; inspect installed versions

VoIP packet-capture methodology

Select interfaces, time windows and paired capture points that distinguish network loss from missing evidence.

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Guide · Current Asterisk logging, runtime command, logger.conf, debug-collection, call-identifier and console-verbosity documentation reviewed September 30, 2026; no process, logger, trace, storage path or call tested

Asterisk logging without permanent debug overload

Map configured destinations, console levels, call identifiers and a bounded protocol trace without leaving sensitive debug collection active.

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VoIP troubleshooting

Use symptoms and evidence to isolate registration, routing, media and device faults.

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