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Asterisk inheritable PJSIP header is missing, duplicated or wrong

Trace branch support, source-channel state, callee creation, per-leg pre-dial mutation, the emitted request and intermediary handling before adding another header copy.

Reviewed 2026-10-14Current Asterisk PJSIP_INHERITABLE_HEADER, PJSIP_HEADER, Dial and pre-dial-handler documentation reviewed October 14, 2026; the inheritable function is documented since Asterisk 20.19.0, 22.9.0 and 23.3.0, is absent from the documented Asterisk 21 function set, and exposes add, update and remove rather than a read action; installed release, loaded module, dialplan owner, channel graph, generated request, intermediary policy and peer acceptance remain deployment specific, and no PBX, module, dialplan, channel, endpoint, header, request, response, packet or call was inspected or testedAdvancedDocumentation based · not lab tested

Freeze one request and its channel graph

Record timestamp and timezone, full Asterisk version, package source, loaded modules, dialplan revision, source channel and unique ID, linked ID, every callee channel, endpoint or contact, handler option, expected header name and value, emitted request, next hop and response. Classify the first mismatch as unavailable function, failed add or update, wrong source channel, missing inheritance, per-leg handler error, duplicate store, later overwrite, intermediary rewrite or peer rejection.

Do not begin by adding the same field through PJSIP_HEADER(). That can create a second independently owned header and hide the original inheritance failure.

Prove branch and module availability first

Confirm a documented supporting release: 20.19.0 or later on branch 20, 22.9.0 or later on branch 22, or 23.3.0 or later on branch 23. Do not infer support from the major number alone; Asterisk 21 documentation does not list the function. Confirm res_pjsip_header_funcs is loaded and the active dialplan actually contains the intended priorities.

A parse error, unknown function or stale dialplan is earlier evidence than a missing packet field. Preserve the error and correct that boundary before changing endpoint or carrier settings.

Check operation preconditions without inventing a read

Verify that add executes before update, because update requires the named inheritable header to exist and can fail the call otherwise. Confirm the instance number when duplicate names are intentional. When removing, record exact-name or wildcard scope and the returned count.

There is no documented read action for this function. Use controlled inputs, dialplan execution evidence and sanitized outbound signaling. An empty attempted read is not proof that inheritance failed.

Follow the value from caller to every callee

Identify the channel where the inheritable header was added and each outbound PJSIP child created afterward. For parallel contacts or endpoints, compare every fork. If a lowercase b() handler is present, prove one execution on each callee, its update or remove result and its required Return().

A value added after the relevant child was created, on a Local-channel sibling, in uppercase B() when per-callee mutation was intended, or on a branch that never sent the request cannot establish the affected leg. Keep call forwarding and nested Dial boundaries visible rather than treating linkedid as shared header state.

Inventory both header stores and the wire result

Search the dialplan and generated logic for both PJSIP_INHERITABLE_HEADER() and PJSIP_HEADER() using the same name. Because each function owns only its own additions, an ordinary remove does not clear an inheritable copy and an inheritable remove does not clear an ordinary copy. Compare the complete sanitized outbound header list before and after the pre-dial handler.

Then compare Asterisk output with the SBC or carrier-facing message. A duplicate can originate in separate dialplan stores or be added by an intermediary; a missing far-side field can be removed after Asterisk emitted it.

Correct one boundary and repeat positive and negative controls

Correct only the demonstrated owner: supporting maintenance release, loaded module, dialplan order, source channel, add-before-update sequence, handler option, per-callee logic, duplicate store or intermediary policy. Repeat the same request, one expected fork and one nearby case that must not receive the header. Confirm the source state, callee mutation, emitted syntax, peer response and final outcome separately.

Remove temporary protocol logging and retain only redacted evidence. Do not broaden identity or routing permissions to make the field appear. No PBX, module, dialplan, channel, endpoint, header, request, response, packet or call was inspected or tested for this diagnostic.

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 Asterisk PJSIP_INHERITABLE_HEADER, PJSIP_HEADER, Dial and pre-dial-handler documentation reviewed October 14, 2026; the inheritable function is documented since Asterisk 20.19.0, 22.9.0 and 23.3.0, is absent from the documented Asterisk 21 function set, and exposes add, update and remove rather than a read action; installed release, loaded module, dialplan owner, channel graph, generated request, intermediary policy and peer acceptance remain deployment specific, and no PBX, module, dialplan, channel, endpoint, header, request, response, packet or call was inspected or tested

Asterisk PJSIP_INHERITABLE_HEADER: channel inheritance and outbound SIP evidence

Add one controlled SIP header on a calling channel, follow it to each outbound PJSIP child, and keep inheritance, callee-specific mutation, emitted signaling and peer acceptance separate.

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Guide · Current Asterisk PJSIP header, inheritable-header, header-list, header-parameter, response-header and pre-dial-handler documentation reviewed October 8, 2026; PJSIP_INHERITABLE_HEADER is documented from 20.19.0, 22.9.0 and 23.3.0, and no PBX, dialplan, channel, header, provider, endpoint, request, response, registration, authentication exchange, availability, compatibility or call was inspected or tested

Asterisk PJSIP outbound headers: channel ownership, inheritance and proof

Put a required SIP header on the channel that will send it, distinguish direct from inherited headers and verify the emitted request.

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Diagnostic · Current Asterisk PJSIP header, inheritable-header, header-list, header-parameter, response-header and pre-dial-handler documentation reviewed October 8, 2026; PJSIP_INHERITABLE_HEADER is documented from 20.19.0, 22.9.0 and 23.3.0, and no PBX, dialplan, channel, header, provider, endpoint, request, response, registration, authentication exchange, availability, compatibility or call was inspected or tested

Asterisk PJSIP required outbound header is missing or duplicated

Trace one outbound request through the caller, callee, handler and header store before changing a trunk or copying inbound data.

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Guide · Current Asterisk PJSIP_HEADER_PARAM, PJSIP_HEADER, PJSIP_PARSE_URI_FROM, CHANNEL, Dial and pre-dial-handler documentation plus RFC 3261 reviewed October 13, 2026; PJSIP_HEADER_PARAM is documented since Asterisk 18.16.0 and 20.1.0 and currently supports only the From header, while installed release, loaded module, dialplan owner, channel leg, parameter contract, endpoint policy, upstream rewriting and emitted SIP remain deployment specific; no PBX, module, endpoint, trunk, dialplan, channel, request, response, packet or call was inspected or tested

Asterisk PJSIP_HEADER_PARAM: From URI and header parameter boundaries

Read or set one documented From parameter on the correct PJSIP channel without confusing URI placement, header placement, caller identity, carrier policy or emitted SIP.

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Guide · Asterisk Latest API PJSIP_DIAL_CONTACTS, Dial, PJSIP_AOR, PJSIP_CONTACT and AMI object documentation plus PJSIP configuration relationships reviewed October 12, 2026; the generated pages reported branch 23, but the installed Asterisk version, endpoint, AoRs, contacts, registration expiry, qualification, dialplan, SIP responses and call legs remain deployment-specific, and no PBX, endpoint, AoR, contact, registration, device, channel, request, response or call was inspected or tested

Asterisk PJSIP_DIAL_CONTACTS: dial every current AoR contact

Build a call-time PJSIP dial string from the intended endpoint and AoR while keeping contact inventory, qualification, outbound channels and the winning answer independently observable.

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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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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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VoIP troubleshooting

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

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