Telnyx Voice Gather - 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).

Add messages to AI Assistant

Add messages to the conversation started by an AI assistant on the call.

POST /calls/{call_control_id}/actions/ai_assistant_add_messages

Optional: client_state (string), command_id (string), messages (array[object])

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/ai_assistant_add_messages"

Returns: result (string)

Start AI Assistant

Start an AI assistant on the call. Expected Webhooks:

• call.conversation.ended
• call.conversation_insights.generated

POST /calls/{call_control_id}/actions/ai_assistant_start

Optional: assistant (object), client_state (string), command_id (string), greeting (string), interruption_settings (object), transcription (object), voice (string), voice_settings (object)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "voice": "Telnyx.KokoroTTS.af",
  "greeting": "Hello, can you tell me your age and where you live?",
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/ai_assistant_start"

Returns: conversation_id (uuid), result (string)

Stop AI Assistant

Stop an AI assistant on the call.

POST /calls/{call_control_id}/actions/ai_assistant_stop

Optional: client_state (string), command_id (string)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/ai_assistant_stop"

Returns: result (string)

Gather

Gather DTMF signals to build interactive menus. You can pass a list of valid digits. The Answer command must be issued before the gather command.

POST /calls/{call_control_id}/actions/gather

Optional: client_state (string), command_id (string), gather_id (string), initial_timeout_millis (int32), inter_digit_timeout_millis (int32), maximum_digits (int32), minimum_digits (int32), terminating_digit (string), timeout_millis (int32), valid_digits (string)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "minimum_digits": 1,
  "maximum_digits": 10,
  "timeout_millis": 60000,
  "inter_digit_timeout_millis": 10000,
  "initial_timeout_millis": 10000,
  "terminating_digit": "#",
  "valid_digits": "123",
  "gather_id": "my_gather_id",
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/gather"

Returns: result (string)

Gather stop

Stop current gather. Expected Webhooks:

• call.gather.ended

POST /calls/{call_control_id}/actions/gather_stop

Optional: client_state (string), command_id (string)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/gather_stop"

Returns: result (string)

Gather using AI

Gather parameters defined in the request payload using a voice assistant. You can pass parameters described as a JSON Schema object and the voice assistant will attempt to gather these informations.

POST /calls/{call_control_id}/actions/gather_using_ai — Required: parameters

Optional: assistant (object), client_state (string), command_id (string), gather_ended_speech (string), greeting (string), interruption_settings (object), language (object), message_history (array[object]), send_message_history_updates (boolean), send_partial_results (boolean), transcription (object), user_response_timeout_ms (integer), voice (string), voice_settings (object)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "parameters": {
    "properties": {
      "age": {
        "description": "The age of the customer.",
        "type": "integer"
      },
      "location": {
        "description": "The location of the customer.",
        "type": "string"
      }
    },
    "required": [
      "age",
      "location"
    ],
    "type": "object"
  },
  "voice": "Telnyx.KokoroTTS.af",
  "greeting": "Hello, can you tell me your age and where you live?",
  "send_partial_results": false,
  "send_message_history_updates": false,
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901",
  "user_response_timeout_ms": 15000,
  "gather_ended_speech": "Thank you for providing the information."
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/gather_using_ai"

Returns: conversation_id (uuid), result (string)

Gather using audio

Play an audio file on the call until the required DTMF signals are gathered to build interactive menus. You can pass a list of valid digits along with an 'invalid_audio_url', which will be played back at the beginning of each prompt. Playback will be interrupted when a DTMF signal is received.

POST /calls/{call_control_id}/actions/gather_using_audio

Optional: audio_url (string), client_state (string), command_id (string), inter_digit_timeout_millis (int32), invalid_audio_url (string), invalid_media_name (string), maximum_digits (int32), maximum_tries (int32), media_name (string), minimum_digits (int32), terminating_digit (string), timeout_millis (int32), valid_digits (string)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "audio_url": "http://example.com/message.wav",
  "media_name": "my_media_uploaded_to_media_storage_api",
  "invalid_audio_url": "http://example.com/invalid.wav",
  "invalid_media_name": "my_media_uploaded_to_media_storage_api",
  "minimum_digits": 1,
  "maximum_digits": 10,
  "maximum_tries": 3,
  "timeout_millis": 60000,
  "terminating_digit": "#",
  "valid_digits": "123",
  "inter_digit_timeout_millis": 10000,
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/gather_using_audio"

Returns: result (string)

Gather using speak

Convert text to speech and play it on the call until the required DTMF signals are gathered to build interactive menus. You can pass a list of valid digits along with an 'invalid_payload', which will be played back at the beginning of each prompt. Speech will be interrupted when a DTMF signal is received.

POST /calls/{call_control_id}/actions/gather_using_speak — Required: voice, payload

Optional: client_state (string), command_id (string), inter_digit_timeout_millis (int32), invalid_payload (string), language (enum: arb, cmn-CN, cy-GB, da-DK, de-DE, en-AU, en-GB, en-GB-WLS, en-IN, en-US, es-ES, es-MX, es-US, fr-CA, fr-FR, hi-IN, is-IS, it-IT, ja-JP, ko-KR, nb-NO, nl-NL, pl-PL, pt-BR, pt-PT, ro-RO, ru-RU, sv-SE, tr-TR), maximum_digits (int32), maximum_tries (int32), minimum_digits (int32), payload_type (enum: text, ssml), service_level (enum: basic, premium), terminating_digit (string), timeout_millis (int32), valid_digits (string), voice_settings (object)

curl \
  -X POST \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "payload": "Say this on the call",
  "invalid_payload": "Say this on the call",
  "payload_type": "ssml",
  "service_level": "premium",
  "voice": "Telnyx.KokoroTTS.af",
  "language": "en-US",
  "minimum_digits": 1,
  "maximum_digits": 10,
  "maximum_tries": 3,
  "timeout_millis": 60000,
  "terminating_digit": "#",
  "valid_digits": "123",
  "inter_digit_timeout_millis": 10000,
  "client_state": "aGF2ZSBhIG5pY2UgZGF5ID1d",
  "command_id": "891510ac-f3e4-11e8-af5b-de00688a4901"
}' \
  "https://api.telnyx.com/v2/calls/{call_control_id}/actions/gather_using_speak"

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
CallAIGatherEnded	Call AI Gather Ended
CallAIGatherMessageHistoryUpdated	Call AI Gather Message History Updated
CallAIGatherPartialResults	Call AI Gather Partial Results
callGatherEnded	Call Gather Ended

Webhook payload fields

CallAIGatherEnded

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.ai_gather.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	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.message_history	array[object]	The history of the messages exchanged during the AI gather
data.payload.result	object	The result of the AI gather, its type depends of the parameters provided in the command
data.payload.status	enum: valid, invalid	Reflects how command ended.

CallAIGatherMessageHistoryUpdated

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.ai_gather.message_history_updated	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	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.message_history	array[object]	The history of the messages exchanged during the AI gather

CallAIGatherPartialResults

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.ai_gather.partial_results	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	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.message_history	array[object]	The history of the messages exchanged during the AI gather
data.payload.partial_results	object	The partial result of the AI gather, its type depends of the parameters provided in the command

callGatherEnded

Field	Type	Description
data.record_type	enum: event	Identifies the type of the resource.
data.event_type	enum: call.gather.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.digits	string	The received DTMF digit or symbol.
data.payload.status	enum: valid, invalid, call_hangup, cancelled, cancelled_amd, timeout	Reflects how command ended.