FreePBX fax: inbound routing, storage and delivery evidence

Start with the installed capability boundary

Sangoma describes the standard Fax Configuration module as an inbound fax-to-email capability and Fax Pro as a commercial extension that adds UCP send, receive and local-management functions. Record the installed module names and versions, license state, enabled features, responsible users and intended workflow before following a screen guide. Do not infer outbound UCP faxing, cover sheets or local folders from the presence of basic inbound fax settings.

Keep the operational contract explicit: dedicated fax DID or mixed voice-and-fax DID, inbound only or bidirectional, email attachment or notification, local retention, UCP access, supported document formats, retry policy and required evidence of delivery.

Route a dedicated DID without unnecessary detection

For a DID used only for fax, Sangoma says fax detection can remain off and the inbound route’s normal destination can be the fax recipient. For a shared voice-and-fax DID, detection attempts to distinguish the call and can delay ordinary voice routing. Record the trunk, called number as received, matching inbound route, detection setting and time, normal destination and fax destination.

Do not treat a visible inbound route as proof that the received Request-URI matched it or that fax detection selected the fax branch. Use the existing inbound-route and fax-over-VoIP diagnostics for signaling, T.38 or audio-transfer failures before investigating delivery after a completed transfer.

Make recipient ownership explicit

The current Sangoma guide places fax-recipient settings in User Management and says the user must be linked to a primary extension, with an unused virtual extension as an option where no device is associated. Record the selected fax recipient, linked extension, fax enablement, destination email, attachment format and local-storage choice.

A route can point to a recipient whose account, linked extension or fax settings no longer match the intended owner. Review access when staff or responsibilities change, and avoid shared credentials merely to expose one inbox.

Separate transfer result from distribution result

Asterisk ReceiveFAX saves a received document as TIFF/F and exposes session results including status, error, detailed status, remote station ID, pages, rate, resolution and whether the session used audio or T.38. Those values establish the fax-session outcome; they do not prove FreePBX converted an attachment, retained a local copy, exposed it in UCP or delivered an email.

Preserve the session timestamp and bounded result fields before following the file into recipient mapping and distribution. A sender report, audible tones or a first page alone is not proof that all pages were received and delivered.

Treat email, storage and UCP as independent controls

Sangoma documents attachment choices, per-user local storage, global and user-level email-result settings, and page quotas. It also documents reject or delete-oldest behavior when local storage is full. Therefore a completed transfer can produce an email without a stored UCP item, a stored item without a usable email, or a quota outcome that differs from both.

Record attachment format, destination address, notification policy, storage choice, quota state and the resulting UCP folder separately. Fax content may be sensitive: restrict access, protect mail and backups, define retention and deletion, and use a non-sensitive test document.

Accept both success and bounded failure

With authorization, test a dedicated or shared DID using a known non-sensitive one-page and multi-page document. Preserve the inbound route, selected destination, Asterisk session result and page count, expected recipient, attachment or notification, local copy and UCP state. For outbound Fax Pro, also preserve the selected user, number normalization, source files, route, retry count and final Asterisk result.

Run one controlled failure that exercises the documented notification or retry policy without sending sensitive content. Confirm cleanup and rollback. The post-receipt diagnostic begins only after evidence says the fax session completed.

Separate Asterisk fax completion from FreePBX delivery

The Asterisk res_fax guide stops at the fax session and TIFF/F artifact. Email, UCP, archive and other FreePBX delivery remain later managed stages requiring their own evidence.