## Initiate a callback

`POST /v1/calls/callback`

Initiates a callback: Bitrix24 first calls the operator line (`fromLine`), and once it is answered, connects the operator to the client (`toNumber`). Used for outbound calls from CRM without dialing the number manually.

## Request fields (body)

| Parameter | Type | Required | Default | Description |
|----------|-----|:-----:|-----------|---------|
| `fromLine` | string | yes | — | Operator line ID. List of lines — [`GET /v1/voximplant-lines`](../lines/voximplant.md) |
| `toNumber` | string | yes | — | Client phone number in international format |

## Examples

### curl — personal key

```bash
curl -X POST https://vibecode.bitrix24.com/v1/calls/callback \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "fromLine": "YOUR_LINE_ID",
    "toNumber": "+12025550123"
  }'
```

### curl — OAuth application

```bash
curl -X POST https://vibecode.bitrix24.com/v1/calls/callback \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "fromLine": "YOUR_LINE_ID",
    "toNumber": "+12025550124"
  }'
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/calls/callback', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    fromLine: 'YOUR_LINE_ID',
    toNumber: '+12025550125',
  }),
})

const { success, data } = await res.json()
const callId = data.callId
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/calls/callback', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    fromLine: 'YOUR_LINE_ID',
    toNumber: '+12025550126',
  }),
})

const { success, data } = await res.json()
const callId = data.callId
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `result` | boolean | `true` when the call is initiated successfully |
| `callId` | string | Identifier of the initiated call with the `callback.` prefix |

## Response example

HTTP 200 — call initiated:

```json
{
  "success": true,
  "data": {
    "result": true,
    "callId": "callback.e7804636435209e12c9cef1ec1bcead1.1777974876"
  }
}
```

## Error response example

400 — required parameters not provided:

```json
{
  "success": false,
  "error": {
    "code": "MISSING_PARAMS",
    "message": "Required: fromLine (string), toNumber (string)"
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `MISSING_PARAMS` | `fromLine` or `toNumber` not provided |
| 401 | `MISSING_API_KEY` | `X-Api-Key` header not provided |
| 401 | `INVALID_API_KEY` | Invalid API key |
| 401 | `TOKEN_MISSING` | The key has no configured Bitrix24 tokens |
| 401 | `KEY_INACTIVE` | API key is inactive or revoked |
| 403 | `SCOPE_DENIED` | The key lacks the `telephony` scope |
| 422 | `BITRIX_ERROR` | Bitrix24 returned an error (message in `error.message`) |
| 429 | `RATE_LIMITED` | Request limit exceeded |
| 502 | `BITRIX_UNAVAILABLE` | Bitrix24 is unavailable |

Full list of common API errors — [Errors](/docs/errors).

## Known specifics

**Connection order.** Bitrix24 first calls the operator line. The client is called only after the operator has answered. If the operator does not answer, the client is not disturbed.

**`callId` prefix.** Callback identifiers start with `callback.` — unlike registered calls (`externalCall.`) and informational ones (`infocall.`).

**Record in statistics.** After the call ends, it appears in the [statistics](../analytics/statistics.md) with `CALL_TYPE: "4"`.

**Real charges.** Each invocation initiates a call to the operator's number and draws on your Bitrix24 account balance.

## See also

- [Auto-call with speech synthesis](./auto-call.md)
- [Auto-call with an audio file](./auto-call-audio.md)
- [Call statistics](../analytics/statistics.md)
- [Voximplant line list](../lines/voximplant.md)