Telnyx Voice Advanced Curl Agent Skill

>- Advanced call control features including DTMF sending, SIPREC recording, noise suppression, client state, and supervisor controls. This skill provides REST API (curl) examples.

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Install

one command, takes just this skill from the repository

npx skills add https://github.com/team-telnyx/ai --skill telnyx-voice-advanced-curl

The instruction itself

15 sections, as written by the author

Telnyx Voice Advanced - curl

Installation

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

Setup

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:

# 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)

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

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)

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)

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)

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)

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)

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

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:

# 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. |