---
title: "Forking start"
method: POST
path: "/calls/{call_control_id}/actions/fork_start"
tags: ["Call Commands"]
---

# Forking start

`POST /calls/{call_control_id}/actions/fork_start`

Call forking allows you to stream the media from a call to a specific target in realtime. 
This stream can be used to enable realtime audio analysis to support a 
variety of use cases, including fraud detection, or the creation of AI-generated audio responses. 
Requests must specify either the `target` attribute or the `rx` and `tx` attributes.

**Expected Webhooks:**

- `call.fork.started`
- `call.fork.stopped`

## Path parameters

- `call_control_id` string, required

## Request body

- StartForkingRequest
  - `rx` string — The network target, <udp:ip_address:port>, where the call's incoming RTP media packets should be forwarded.
  - `stream_type` 'decrypted' — Optionally specify a media type to stream. If `decrypted` selected, Telnyx will decrypt incoming SIP media before forking to the target. `rx` and `tx` are required fields if `decrypted` selected.
  - `tx` string — The network target, <udp:ip_address:port>, where the call's outgoing RTP media packets should be forwarded.
  - `client_state` string — Use this field to add state to every subsequent webhook. It must be a valid Base-64 encoded string.
  - `command_id` string — Use this field to avoid duplicate commands. Telnyx will ignore any command with the same `command_id` for the same `call_control_id`.

## Response `200`

Successful response upon making a call control command.

- object
  - `data` CallControlCommandResult
    - `result` string

## Other responses

- `422` — Unprocessable entity. The request was well-formed but could not be processed due to semantic errors. This includes validation errors, invalid parameter values, call state errors, conference errors, queue errors, recording/transcription errors, and business logic violations.
- `default` — Unexpected error

---

[API](https://skmtc.dev/team-telnyx/apis/telnyx-api.md) · [All operations](https://skmtc.dev/team-telnyx/apis/telnyx-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/team-telnyx/telnyx-api/revisions/e32d46c5945b/schema)