---
name: telnyx-voice-streaming-curl
description: >-
  Stream call audio in real-time, fork media to external destinations, and
  transcribe speech live. Use for real-time analytics and AI integrations. This
  skill provides REST API (curl) examples.
metadata:
  author: telnyx
  product: voice-streaming
  language: curl
  generated_by: telnyx-ext-skills-generator
---

<!-- Auto-generated from Telnyx OpenAPI specs. Do not edit. -->

# Telnyx Voice Streaming - curl

## Installation

```text
# curl is pre-installed on macOS, Linux, and Windows 10+
```

## Setup

```bash
export TELNYX_API_KEY="YOUR_API_KEY_HERE"
```

All examples below use `$TELNYX_API_KEY` for authentication.

## Error Handling

All API calls can fail with network errors, rate limits (429), validation errors (422),
or authentication errors (401). Always handle errors in production code:

```bash
# Check HTTP status code in response
response=$(curl -s -w "\n%{http_code}" \
  -X POST "https://api.telnyx.com/v2/messages" \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"to": "+13125550001", "from": "+13125550002", "text": "Hello"}')

http_code=$(echo "$response" | tail -1)
body=$(echo "$response" | sed '$d')

case $http_code in
  2*) echo "Success: $body" ;;
  422) echo "Validation error — check required fields and formats" ;;
  429) echo "Rate limited — retry after delay"; sleep 1 ;;
  401) echo "Authentication failed — check TELNYX_API_KEY" ;;
  *)   echo "Error $http_code: $body" ;;
esac
```

Common error codes: `401` invalid API key, `403` insufficient permissions,
`404` resource not found, `422` validation error (check field formats),
`429` rate limited (retry with exponential backoff).

## Forking 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.

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

Optional: `client_state` (string), `command_id` (string), `rx` (string), `stream_type` (enum: decrypted), `tx` (string)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/fork_start"
```

Returns: `result` (string)

## Forking stop

Stop forking a call. **Expected Webhooks:**

- `call.fork.stopped`

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

Optional: `client_state` (string), `command_id` (string), `stream_type` (enum: raw, decrypted)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/fork_stop"
```

Returns: `result` (string)

## Streaming start

Start streaming the media from a call to a specific WebSocket address or Dialogflow connection in near-realtime. Audio will be delivered as base64-encoded RTP payload (raw audio), wrapped in JSON payloads. Please find more details about media streaming messages specification under the [link](https://developers.telnyx.com/docs/voice/programmable-voice/media-streaming).

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

Optional: `client_state` (string), `command_id` (string), `custom_parameters` (array[object]), `dialogflow_config` (object), `enable_dialogflow` (boolean), `stream_auth_token` (string), `stream_bidirectional_codec` (enum: PCMU, PCMA, G722, OPUS, AMR-WB, L16), `stream_bidirectional_mode` (enum: mp3, rtp), `stream_bidirectional_sampling_rate` (enum: 8000, 16000, 22050, 24000, 48000), `stream_bidirectional_target_legs` (enum: both, self, opposite), `stream_codec` (enum: PCMU, PCMA, G722, OPUS, AMR-WB, L16, default), `stream_track` (enum: inbound_track, outbound_track, both_tracks), `stream_url` (string)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
      "stream_url": "wss://example.com/audio-stream"
  }' \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/streaming_start"
```

Returns: `result` (string)

## Streaming stop

Stop streaming a call to a WebSocket. **Expected Webhooks:**

- `streaming.stopped`

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

Optional: `client_state` (string), `command_id` (string), `stream_id` (uuid)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/streaming_stop"
```

Returns: `result` (string)

## Transcription start

Start real-time transcription. Transcription will stop on call hang-up, or can be initiated via the Transcription stop command. **Expected Webhooks:**

- `call.transcription`

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

Optional: `client_state` (string), `command_id` (string), `transcription_engine` (enum: Google, Telnyx, Deepgram, Azure, A, B), `transcription_engine_config` (object), `transcription_tracks` (string)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/transcription_start"
```

Returns: `result` (string)

## Transcription stop

Stop real-time transcription.

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

Optional: `client_state` (string), `command_id` (string)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/transcription_stop"
```

Returns: `result` (string)

---

## Webhooks

### Webhook Verification

Telnyx signs webhooks with Ed25519. Each request includes `telnyx-signature-ed25519`
and `telnyx-timestamp` headers. Always verify signatures in production:

```bash
# Telnyx signs webhooks with Ed25519 (asymmetric — NOT HMAC/Standard Webhooks).
# Headers sent with each webhook:
#   telnyx-signature-ed25519: base64-encoded Ed25519 signature
#   telnyx-timestamp: Unix timestamp (reject if >5 minutes old for replay protection)
#
# Get your public key from: Telnyx Portal > Account Settings > Keys & Credentials
# Use the Telnyx SDK in your language for verification (client.webhooks.unwrap).
# Your endpoint MUST return 2xx within 2 seconds or Telnyx will retry (up to 3 attempts).
# Configure a failover URL in Telnyx Portal for additional reliability.
```

The following webhook events are sent to your configured webhook URL.
All webhooks include `telnyx-timestamp` and `telnyx-signature-ed25519` headers for Ed25519 signature verification. Use `client.webhooks.unwrap()` to verify.

| Event | Description |
|-------|-------------|
| `callForkStarted` | Call Fork Started |
| `callForkStopped` | Call Fork Stopped |
| `callStreamingFailed` | Call Streaming Failed |
| `callStreamingStarted` | Call Streaming Started |
| `callStreamingStopped` | Call Streaming Stopped |
| `transcription` | Transcription |

### Webhook payload fields

**`callForkStarted`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.fork.started | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.call_control_id` | string | Unique ID for controlling the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.stream_type` | enum: decrypted | Type of media streamed. |

**`callForkStopped`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.fork.stopped | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.call_control_id` | string | Unique ID for controlling the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.stream_type` | enum: decrypted | Type of media streamed. |

**`callStreamingFailed`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the resource. |
| `data.event_type` | enum: streaming.failed | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.call_control_id` | string | Call ID used to issue commands via Call Control API. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.failure_reason` | string | A short description explaning why the media streaming failed. |
| `data.payload.stream_id` | uuid | Identifies the streaming. |
| `data.payload.stream_type` | enum: websocket, dialogflow | The type of stream connection the stream is performing. |

**`callStreamingStarted`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: streaming.started | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.call_control_id` | string | Call ID used to issue commands via Call Control API. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.stream_url` | string | Destination WebSocket address where the stream is going to be delivered. |

**`callStreamingStopped`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: streaming.stopped | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.call_control_id` | string | Call ID used to issue commands via Call Control API. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.stream_url` | string | Destination WebSocket address where the stream is going to be delivered. |

**`transcription`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.transcription | The type of event being delivered. |
| `data.id` | uuid | Identifies the type of resource. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.payload.call_control_id` | string | Unique identifier and token for controlling the call. |
| `data.payload.call_leg_id` | string | ID that is unique to the call and can be used to correlate webhook events. |
| `data.payload.call_session_id` | string | ID that is unique to the call session and can be used to correlate webhook events. |
| `data.payload.client_state` | string | Use this field to add state to every subsequent webhook. |
| `data.payload.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |