> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://developer.jelliu.co/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://developer.jelliu.co/_mcp/server.

# Cancel a warm transfer

POST https://api.jelliu.co/api/calls/{callId}/transfer/cancel

Hangs up the human leg and returns the caller to the AI: a fresh voice-provider conversation is registered on the caller's leg with the call's agent, and the transfer fields are cleared.

**Side effects.** Ends the human's carrier leg, starts a new AI conversation on the same call row (the row now points at the new conversation, whose post-call data replaces the old one), and writes an audit entry.

The AI can only be resumed when the call's agent still exists, is provisioned and is not paused. Those refusals currently surface as **502** (not 409): they are raised after the human leg has already been hung up and are wrapped as a telephony error, so on a 502 the caller may be left in the conference alone. Check the agent's state before canceling.

**Idempotency.** Not safe to repeat blindly: after a success the transfer fields are cleared and a repeat returns 400 `No active transfer to cancel`; after a 502 the human leg may already be gone.

**Access**
- **Required scope:** `full`. Signed-in users need the admin or owner role.
- **Rate limit:** Outbound — 20 requests/min per workspace, and also the General API budget (per plan: 120 to 600 requests/min per workspace). See [Rate limits](/rate-limits).
- **Plan:** Available on every plan.


Reference: https://developer.jelliu.co/api-reference/calls/post-calls-by-call-id-transfer-cancel

## Authentication

- `Authorization` header (bearer token, required) — Workspace API key: `jl_` followed by 64 lowercase hex characters, created by the workspace owner in the dashboard (**Settings → API Keys**) and sent as `Authorization: Bearer jl_...`. The plaintext is shown once, at creation; Jelliu stores only a SHA-256 hash. A workspace can hold up to 25 active keys. | Scope | GET / HEAD | POST / PUT / PATCH / DELETE | Admin-only routes | | --- | --- | --- | --- | | `read` | Yes | No | No | | `write` | Yes | Yes | No | | `full` | Yes | Yes | Yes | Operations restricted to admins or owners reject keys without the `full` scope with `403`, and say so in their description. No key, whatever its scope, can mint or revoke API keys or rotate a webhook secret — that requires a signed-in owner session. A revoked key stops authenticating within about 10 seconds. See [Authentication](/authentication).

## Request

### Path parameters

- `callId` (string, required) — The transferred call's id. Must be a UUID (400 `Invalid call ID` otherwise).

## Response

### 200

Transfer canceled and the AI is back on the line. Note this body has no `data` wrapper.

- `success` (true, required) — Always `true`.
- `message` (string, required) — Fixed confirmation text.

## Errors

### 400 Bad Request Error

Invalid `callId`, or the call has no active transfer.

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

### 401 Unauthorized Error

No usable credential. Either the `Authorization` header is missing or is not a well-formed `Bearer jl_…` key, or the key is unknown, revoked or expired. Do not retry with the same key. See [Authentication](/authentication#401-unauthorized).

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

### 403 Forbidden Error

The API key lacks the `full` scope, or the signed-in user is not an admin or owner.

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

### 404 Not Found Error

The call does not exist or belongs to another workspace.

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

### 429 Too Many Requests Error

The outbound budget (20 requests/min) or the general budget is spent.

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

### 502 Bad Gateway Error

The carrier or voice provider rejected a step, or the AI could not be resumed because the call's agent is paused or not provisioned (`TELEPHONY_ERROR`; message replaced by `Internal server error`). The human leg may already have been hung up.

- `error` (object, required) — The error object. Always has `code` and `message`.
  - `code` (string, required) — Stable machine-readable error code (for example `VALIDATION_FAILED`, `UNAUTHORIZED`, `FORBIDDEN`, `NOT_FOUND`, `BILLING_ERROR`, `COMPLIANCE_BLOCKED`, `RATE_LIMIT_EXCEEDED`, `INTERNAL_ERROR`). Switch on this, not on `message`. See [Errors](/errors).
  - `message` (string, required) — Human-readable explanation. English or Spanish depending on the route; may change without notice.
  - `details` (object or list of object, optional) — Present on `VALIDATION_FAILED` only. Its shape depends on how the route validates: * a field map, either Zod's `flatten()` output (`{ "formErrors": [], "fieldErrors": { "name": ["..."] } }`) or just its `fieldErrors` part (`{ "name": ["..."] }`); * an issue list, where each issue has at least `path`, `message` and `code`. `path` is a dot-separated string on routes that let the schema throw, and an array of keys on routes that forward Zod's raw issues (those also carry Zod's extra issue fields).
    - Field map
      - `formErrors` (list of string, optional)
      - `fieldErrors` (map from string to list of string, optional)
  - `metadata` (map from string to any, optional) — Structured detail exposed for a small allowlist of codes only — for example `BILLING_ERROR` carries `limit`, `current` and `tier` (resource caps) or `tier` and `feature` (feature gates).

## Examples

**Response**

```json
{
  "success": true,
  "message": "Transfer canceled — AI agent resumed"
}
```

**SDK Code**

```python Calls_postCallsByCallIdTransferCancel_example
import requests

url = "https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel"

headers = {"Authorization": "Bearer <token>"}

response = requests.post(url, headers=headers)

print(response.json())
```

```javascript Calls_postCallsByCallIdTransferCancel_example
const url = 'https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel';
const options = {method: 'POST', headers: {Authorization: 'Bearer <token>'}};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go Calls_postCallsByCallIdTransferCancel_example
package main

import (
	"fmt"
	"net/http"
	"io"
)

func main() {

	url := "https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel"

	req, _ := http.NewRequest("POST", url, nil)

	req.Header.Add("Authorization", "Bearer <token>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby Calls_postCallsByCallIdTransferCancel_example
require 'uri'
require 'net/http'

url = URI("https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'

response = http.request(request)
puts response.read_body
```

```java Calls_postCallsByCallIdTransferCancel_example
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel")
  .header("Authorization", "Bearer <token>")
  .asString();
```

```php Calls_postCallsByCallIdTransferCancel_example
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel', [
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

echo $response->getBody();
```

```csharp Calls_postCallsByCallIdTransferCancel_example
using RestSharp;

var client = new RestClient("https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
IRestResponse response = client.Execute(request);
```

```swift Calls_postCallsByCallIdTransferCancel_example
import Foundation

let headers = ["Authorization": "Bearer <token>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://api.jelliu.co/api/calls/8d0f3c1e-5b7a-4c52-9d0e-2a6f1b3c4d5e/transfer/cancel")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```