v52

OpenAPI 3.1.0raw.githubusercontent.com2026-07-311,1941,9384.1 MB

Callbacks

Fax Delivered

This webhook uses Telnyx headers (telnyx-timestamp, telnyx-signature-ed25519) that are compatible with Standard Webhooks specification for SDK generation. Custom validation logic can map these to standard webhook-timestamp and webhook-signature equivalents. See https://github.com/standard-webhooks/standard-webhooks for details.

postWebhookfax.delivered

Headers

telnyx-timestampinteger required

Unix timestamp for replay attack prevention

Unix timestamp (seconds since epoch) of when the webhook was sent - compatible with webhook-timestamp

telnyx-signature-ed25519string required

Ed25519 signature of timestamp|payload for verification

Base64 encoded Ed25519 signature for webhook verification - compatible with webhook-signature

Payload

Example payload

{
  "data": {
    "event_type": "fax.delivered",
    "id": "95479a2e-b947-470a-a88f-2da6dd07ae0f",
    "occurred_at": "2020-05-05T13:08:22.039204Z",
    "payload": {
      "call_duration_secs": 25,
      "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
      "connection_id": "234423",
      "direction": "outbound",
      "fax_id": "f8338808-3dc6-4f2b-942a-5d1f39255784",
      "from": "+17733372107",
      "original_media_url": "http://www.example.com/fax.pdf",
      "page_count": 2,
      "status": "delivered",
      "to": "+15107882622",
      "user_id": "19a75cea-02c6-4b9a-84fa-c9bc8341feb8"
    },
    "record_type": "event"
  },
  "meta": {
    "attempt": 1,
    "delivered_to": "https://www.example.com/webhooks"
  }
}

Response

The server must return an HTTP 200, otherwise we will reattempt delivery at the failover webhook URL.