VoIP.infoThe independent guide to business communications.
VoIP.info Guide

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.

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

Confirm the fax stack and observation window first

Record the responding node, exact Asterisk build, loaded res_fax and technology module, dialplan application, manager identity and a synchronized capture window. The three AMI actions are provided by res_fax; their presence does not prove that a particular technology module, route, TIFF/F file or notification path is usable.

Keep manager ActionID, fax SessionNumber, channel name, Uniqueid, Linkedid, FAXOPT(sessionid) and document filename as distinct identifiers. Join them only where retained records establish the relationship.

Close FAXSessions only with its completion event

FAXSessions lists active sessions as FAXSessionsEntry events and closes with FAXSessionsComplete. Retain one unique ActionID, every matching entry and the completion event, then compare Total with the number of retained entries. Each entry can carry channel, technology, session number, G.711 or T.38 session type, operation, state and associated files.

This is a point-in-time active-session inventory. An empty completed list can be correct after a fast session has ended, while an incomplete or filtered list cannot establish that no fax was active.

Use FAXSession for one technology-aware detail snapshot

FAXSession addresses one numerical SessionNumber and returns the FAXSession event. Documented fields include operation, current state and, when applicable, error-correction mode, data rate, image resolution, current page, filename, transmitted or received pages and bad-line count. A fax technology without a FAXSession handler can make the action fail.

Fields are conditional and some values change while the fax progresses. A detail snapshot is not a terminal result, a durable history record or proof that the named file was delivered.

Interpret FAXStats as process counters, not a ledger

FAXStats returns CurrentSessions, ReservedSessions, TransmitAttempts, ReceiveAttempts, CompletedFAXes and FailedFAXes. Store the sample time, node identity, build, process lifetime and raw values before calculating a delta.

These are non-technology-specific runtime statistics. They do not identify an individual fax, expose a time range, prove persistence across restart or support billing, compliance or service-level claims without separately validated retention and attribution.

Keep progress, completion and document evidence separate

FAXStatus is raised periodically during a transmission and reports a channel snapshot, operation, descriptive status, local station ID and filename. ReceiveFAX() and SendFAX() publish terminal FAXSTATUS, FAXERROR, status text, stations, pages, rate, resolution and AUDIO or T38 mode; FAXOPT can retrieve completed-session information such as pages, status and session ID.

A current page count, Complete state or incremented global success counter does not by itself prove a readable TIFF/F file, downstream email, UCP copy, human receipt or remote business acceptance.

Collect least privilege and privacy-safe evidence

Use a dedicated least-privilege AMI identity with only required action and event classes, explicit source restrictions and narrow filters. Redact phone numbers, station IDs, account codes, channel names and document paths while retaining ActionID, session number, timestamps, completion markers, counter context and repair evidence.

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. Validate the contract on one authorized disposable fax path before relying on dashboards or alerts.

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 · 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 res_fax: session options, mode and result evidence

Keep the generic res_fax layer, loaded technology resource, per-session FAXOPT policy, TIFF/F file, audio or T.38 mode and final transmission result independently observable.

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

Fax over VoIP: T.38 relay versus G.711 passthrough

Choose a fax path from end-to-end support and observed document delivery, not a codec checkbox.

Read guide →
Guide · Asterisk branch-23-generated and branch-22-generated ListCommands references plus official AMI syntax, v2 specification, manager-command, change/versioning, permission, module-loader and network-security documentation reviewed October 16, 2026; installed branch and maintenance release, build, package and module set, manager user, read and write authorizations, session mask, action registration, request framing, parameters, target objects, response, related events and service outcome remain deployment specific; no PBX, module, package, manager user, manager session, request, response, event, configuration file, channel, packet, media stream or live call was inspected or tested

Asterisk AMI command inventory and permission evidence

Use ListCommands and the administrator CLI to distinguish the actions visible to one manager user from the actions registered by the running Asterisk instance.

Read guide →
Guide · 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 event delivery, filters and WaitEvent

Trace event delivery through manager read permissions, login and Events masks, configured and session filters, TCP or HTTP transport, WaitEvent queueing and client processing without treating silence as a failed PBX.

Read guide →
Guide · Current Asterisk branch-23-generated CoreShowChannelMap, CoreShowChannelMapComplete, CoreShowChannels, CoreShowChannel, CoreShowChannelsComplete, Status, StatusComplete, Newchannel and Rename references plus the branch 22 map action and completion event reviewed October 16, 2026; installed branch, loaded actions and events, manager permissions, session ordering, channel names, stable identifiers, bridge membership, variables, signaling and media remain deployment specific; no PBX, AMI session, manager user, permission, channel, bridge, variable, packet, media stream or live call was inspected or tested

Asterisk AMI channel snapshots and connected maps

Choose CoreShowChannels, CoreShowChannelMap or Status deliberately, preserve list boundaries, and correlate mutable channel, linked and bridge identities without treating a snapshot as a final call result.

Read guide →
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.

Read guide →
Guide · Operational guidance; Asterisk 22 / FreePBX 17 where applicable

Least privilege for PBX users and integrations

Separate the right to register, place calls, administer the PBX and read sensitive data.

Read guide →
Troubleshooting · 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 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.

Read guide →