---
title: call.supervision.started
description: >-
  Fires when the supervisor answers and joins a live call in listen, whisper or
  barge mode.
summary: >-
  Emitted when the supervisor leg connects. Carries connected_at, the moment
  billing for the supervisor leg starts.
date: 2026-09-30T00:00:00.000Z
type: webhook-event
---


## Summary

`call.supervision.started` fires when the supervisor answers and is on the call in the requested `mode`. From this moment they hear both sides, and the supervisor leg is billed until the supervision ends.

This event is subscribable as a workspace webhook: add `call.supervision.started` to the `events` of a subscription created with [Create a webhook](/developers/api/createWebhook). Supervision events are subscribed by name; there is no `call.supervision.*` wildcard. Delivery is at least once, so deduplicate on the `X-Sautikit-Event-Id` header.

## Payload

The body is flat. The event kind travels in the `X-Sautikit-Event-Kind` header.

```json
{
  "workspace_id": "01900000-0000-7000-8000-000000000002",
  "call_id": "9d2b1f53-8c0e-4f1d-9a6b-5d3a8c47e9f0",
  "session_id": "HD_24d73b4518bc",
  "supervision_id": "0f6d3c1e-5a8b-4c2d-9e7f-1a2b3c4d5e6f",
  "mode": "listen",
  "supervisor": {
    "type": "client",
    "identity": "mary",
    "label": "Mary Wanjiku"
  },
  "occurred_at": "2026-09-30T09:15:04Z",
  "connected_at": "2026-09-30T09:15:04Z"
}
```

Every supervision event carries `workspace_id`, `call_id` (the supervised call's UUID), `session_id` (its `HD_` session id), `supervision_id`, `mode`, `supervisor` (`type`, then `identity` for `client` and `sip` or `number` for `phone`, and `label` when you set one) and `occurred_at`.

## Fields

| Field | Type | Description |
|---|---|---|
| `connected_at` | string (RFC 3339) | When the supervisor answered. Billing for the supervisor leg starts here. |


## Headers

| Header | Description |
|---|---|
| `X-Sautikit-Event-Id` | UUID of the event. Use it to deduplicate. |
| `X-Sautikit-Event-Kind` | `call.supervision.started` |
| `X-Sautikit-Delivery-Id` | UUID of this delivery. |
| `X-Sautikit-Attempt` | Attempt number, starting at `1`. |
| `X-Sautikit-Timestamp` | Unix time the delivery was signed. |
| `X-Sautikit-Signature` | `t=<timestamp>,v1=<hex HMAC-SHA256>`. See [Verify webhook signatures](/developers/guides/verify-webhook-signatures). |

## Next steps

- [Supervise live calls](/developers/guides/supervise-live-calls): start, switch and stop supervision.
- [Webhook concepts](/developers/concepts/webhooks): delivery, retries and subscriptions.