---
name: telnyx-voice-advanced-curl
description: >-
  Advanced call control features including DTMF sending, SIPREC recording, noise
  suppression, client state, and supervisor controls. This skill provides REST
  API (curl) examples.
metadata:
  author: telnyx
  product: voice-advanced
  language: curl
  generated_by: telnyx-ext-skills-generator
---

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

# Telnyx Voice Advanced - 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).

## Join AI Assistant Conversation

Add a participant to an existing AI assistant conversation. Use this command to bring an additional call leg into a running AI conversation.

`POST /calls/{call_control_id}/actions/ai_assistant_join` — Required: `conversation_id`, `participant`

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

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "conversation_id": "v3:abc123",
  "participant": {}
}' \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/ai_assistant_join"
```

Returns: `conversation_id` (uuid), `result` (string)

## Update client state

Updates client state

`PUT /calls/{call_control_id}/actions/client_state_update` — Required: `client_state`

```bash
curl \
  -X PUT \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d"
}' \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/client_state_update"
```

Returns: `result` (string)

## Send DTMF

Sends DTMF tones from this leg. DTMF tones will be heard by the other end of the call. **Expected Webhooks:**

There are no webhooks associated with this command.

`POST /calls/{call_control_id}/actions/send_dtmf` — Required: `digits`

Optional: `client_state` (string), `command_id` (string), `duration_millis` (int32)

```bash
curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "digits": "1www2WABCDw9"
}' \
  "https://api.telnyx.com/v2/calls/v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ/actions/send_dtmf"
```

Returns: `result` (string)

## SIPREC start

Start siprec session to configured in SIPREC connector SRS. 

**Expected Webhooks:**

- `siprec.started`
- `siprec.stopped`
- `siprec.failed`

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

Optional: `client_state` (string), `connector_name` (string), `include_metadata_custom_headers` (boolean), `secure` (boolean), `session_timeout_secs` (integer), `sip_transport` (enum: udp, tcp, tls), `siprec_track` (enum: inbound_track, outbound_track, both_tracks)

```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/siprec_start"
```

Returns: `result` (string)

## SIPREC stop

Stop SIPREC session. **Expected Webhooks:**

- `siprec.stopped`

`POST /calls/{call_control_id}/actions/siprec_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/siprec_stop"
```

Returns: `result` (string)

## Noise Suppression Start (BETA)

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

Optional: `client_state` (string), `command_id` (string), `direction` (enum: inbound, outbound, both), `noise_suppression_engine` (enum: Denoiser, DeepFilterNet, Krisp, AiCoustics), `noise_suppression_engine_config` (object)

```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/suppression_start"
```

Returns: `result` (string)

## Noise Suppression Stop (BETA)

`POST /calls/{call_control_id}/actions/suppression_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/suppression_stop"
```

Returns: `result` (string)

## Switch supervisor role

Switch the supervisor role for a bridged call. This allows switching between different supervisor modes during an active call

`POST /calls/{call_control_id}/actions/switch_supervisor_role` — Required: `role`

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

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 |
|-------|-------------|
| `callConversationEnded` | Call Conversation Ended |
| `callConversationInsightsGenerated` | Call Conversation Insights Generated |
| `callDtmfReceived` | Call Dtmf Received |
| `callMachineDetectionEnded` | Call Machine Detection Ended |
| `callMachineGreetingEnded` | Call Machine Greeting Ended |
| `callMachinePremiumDetectionEnded` | Call Machine Premium Detection Ended |
| `callMachinePremiumGreetingEnded` | Call Machine Premium Greeting Ended |
| `callReferCompleted` | Call Refer Completed |
| `callReferFailed` | Call Refer Failed |
| `callReferStarted` | Call Refer Started |
| `callSiprecFailed` | Call Siprec Failed |
| `callSiprecStarted` | Call Siprec Started |
| `callSiprecStopped` | Call Siprec Stopped |

### Webhook payload fields

**`callConversationEnded`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.conversation.ended | The type of event being delivered. |
| `data.id` | uuid | Unique identifier for the event. |
| `data.occurred_at` | date-time | ISO 8601 datetime of when the event occurred. |
| `data.created_at` | date-time | Timestamp when the event was created in the system. |
| `data.payload.assistant_id` | string | Unique identifier of the assistant involved in the call. |
| `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 leg. |
| `data.payload.call_session_id` | string | ID that is unique to the call session (group of related call legs). |
| `data.payload.client_state` | string | Base64-encoded state received from a command. |
| `data.payload.calling_party_type` | enum: pstn, sip | The type of calling party connection. |
| `data.payload.conversation_id` | string | ID unique to the conversation or insight group generated for the call. |
| `data.payload.duration_sec` | integer | Duration of the conversation in seconds. |
| `data.payload.from` | string | The caller's number or identifier. |
| `data.payload.to` | string | The callee's number or SIP address. |
| `data.payload.llm_model` | string | The large language model used during the conversation. |
| `data.payload.stt_model` | string | The speech-to-text model used in the conversation. |
| `data.payload.tts_provider` | string | The text-to-speech provider used in the call. |
| `data.payload.tts_model_id` | string | The model ID used for text-to-speech synthesis. |
| `data.payload.tts_voice_id` | string | Voice ID used for TTS. |

**`callConversationInsightsGenerated`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.conversation_insights.generated | 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.calling_party_type` | enum: pstn, sip | The type of calling party connection. |
| `data.payload.insight_group_id` | string | ID that is unique to the insight group being generated for the call. |
| `data.payload.results` | array[object] | Array of insight results being generated for the call. |

**`callDtmfReceived`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.dtmf.received | 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 | Identifies the type of resource. |
| `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.from` | string | Number or SIP URI placing the call. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |
| `data.payload.digit` | string | The received DTMF digit or symbol. |

**`callMachineDetectionEnded`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.machine.detection.ended | 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.from` | string | Number or SIP URI placing the call. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |
| `data.payload.result` | enum: human, machine, not_sure | Answering machine detection result. |

**`callMachineGreetingEnded`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.machine.greeting.ended | 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.from` | string | Number or SIP URI placing the call. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |
| `data.payload.result` | enum: beep_detected, ended, not_sure | Answering machine greeting ended result. |

**`callMachinePremiumDetectionEnded`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.machine.premium.detection.ended | 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.from` | string | Number or SIP URI placing the call. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |
| `data.payload.result` | enum: human_residence, human_business, machine, silence, fax_detected, not_sure | Premium Answering Machine Detection result. |

**`callMachinePremiumGreetingEnded`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.machine.premium.greeting.ended | 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.from` | string | Number or SIP URI placing the call. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |
| `data.payload.result` | enum: beep_detected, no_beep_detected | Premium Answering Machine Greeting Ended result. |

**`callReferCompleted`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.refer.completed | 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 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.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.from` | string | Number or SIP URI placing the call. |
| `data.payload.sip_notify_response` | integer | SIP NOTIFY event status for tracking the REFER attempt. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |

**`callReferFailed`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.refer.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 | 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.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.from` | string | Number or SIP URI placing the call. |
| `data.payload.sip_notify_response` | integer | SIP NOTIFY event status for tracking the REFER attempt. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |

**`callReferStarted`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: call.refer.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 | 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.connection_id` | string | Call Control App ID (formerly Telnyx connection ID) used in the call. |
| `data.payload.client_state` | string | State received from a command. |
| `data.payload.from` | string | Number or SIP URI placing the call. |
| `data.payload.sip_notify_response` | integer | SIP NOTIFY event status for tracking the REFER attempt. |
| `data.payload.to` | string | Destination number or SIP URI of the call. |

**`callSiprecFailed`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the resource. |
| `data.event_type` | enum: siprec.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_cause` | string | Q850 reason why siprec session failed. |

**`callSiprecStarted`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: siprec.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. |

**`callSiprecStopped`**

| Field | Type | Description |
|-------|------|-------------|
| `data.record_type` | enum: event | Identifies the type of the resource. |
| `data.event_type` | enum: siprec.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.hangup_cause` | string | Q850 reason why the SIPREC session was stopped. |