Telnyx Voice Advanced Javascript

Telnyx Voice Advanced - JavaScript

Installation

npm install telnyx@6.74.2

Setup

import Telnyx from 'telnyx';

const client = new Telnyx({
  apiKey: process.env['TELNYX_API_KEY'], // This is the default and can be omitted
});

All examples below assume client is already initialized as shown above.

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:

try {
  const result = await client.messages.send({ to: '+13125550001', from: '+13125550002', text: 'Hello' });
} catch (err) {
  if (err instanceof Telnyx.APIConnectionError) {
    console.error('Network error — check connectivity and retry');
  } else if (err instanceof Telnyx.RateLimitError) {
    // 429: rate limited — wait and retry with exponential backoff
    const retryAfter = err.headers?.['retry-after'] || 1;
    await new Promise(r => setTimeout(r, retryAfter * 1000));
  } else if (err instanceof Telnyx.APIError) {
    console.error(`API error ${err.status}: ${err.message}`);
    if (err.status === 422) {
      console.error('Validation error — check required fields and formats');
    }
  }
}

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)

const response = await client.calls.actions.joinAIAssistant('call_control_id', {
  conversation_id: 'v3:abc123',
  participant: { id: 'v3:abc123def456', role: 'user' },
});

console.log(response.data);

Returns: conversation_id (uuid), result (string)

Update client state

Updates client state

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

const response = await client.calls.actions.updateClientState('call_control_id', {
  client_state: 'aGF2ZSBhIG5pY2UgZGF5ID1d',
});

console.log(response.data);

Returns: result (string)

Start Conversation Relay

Start a Conversation Relay session on an active call. Conversation Relay connects the call audio to your WebSocket so your application can exchange realtime messages with the caller while Telnyx handles speech recognition and text-to-speech. Only one AI Assistant or Conversation Relay session can be active on a call at a time.

POST /calls/{call_control_id}/actions/conversation_relay_start

Optional: assistant (object), client_state (string), command_id (string), conversation_relay_dtmf_detection (boolean), conversation_relay_settings (object), conversation_relay_url (string), custom_parameters (object), dtmf_detection (boolean), greeting (string), interruptible (enum: none, any, speech, dtmf), interruptible_greeting (enum: none, any, speech, dtmf), interruption_settings (object), language (string), languages (array[object]), provider (string), structured_provider (object), transcription (object), transcription_engine (enum: Google, Telnyx, Deepgram, Azure, xAI, AssemblyAI, Speechmatics, Soniox, A, B), transcription_engine_config (object), tts_provider (string), url (string), voice (string), voice_settings (object)

const response = await client.calls.actions.startConversationRelay('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

Returns: conversation_relay_id (string), result (string)

Stop Conversation Relay

Stop the active Conversation Relay session on a call.

POST /calls/{call_control_id}/actions/conversation_relay_stop

Optional: client_state (string), command_id (string)

const response = await client.calls.actions.stopConversationRelay('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

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)

const response = await client.calls.actions.sendDtmf('call_control_id', { digits: '1www2WABCDw9' });

console.log(response.data);

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)

const response = await client.calls.actions.startSiprec('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

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)

const response = await client.calls.actions.stopSiprec('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

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, aic_l_quail, aic_l_rook, aic_s_quail, aic_s_rook, quail_voice_focus_s, quail_voice_focus_xs), noise_suppression_engine_config (object)

const response = await client.calls.actions.startNoiseSuppression('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

Returns: result (string)

Noise Suppression Stop (BETA)

POST /calls/{call_control_id}/actions/suppression_stop

Optional: client_state (string), command_id (string)

const response = await client.calls.actions.stopNoiseSuppression('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

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

const response = await client.calls.actions.switchSupervisorRole('call_control_id', {
  role: 'barge',
});

console.log(response.data);

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:

// In your webhook handler (e.g., Express — use raw body, not parsed JSON):
app.post('/webhooks', express.raw({ type: 'application/json' }), async (req, res) => {
  try {
    const event = await client.webhooks.unwrap(req.body.toString(), {
      headers: req.headers,
    });
    // Signature valid — event is the parsed webhook payload
    console.log('Received event:', event.data.event_type);
    res.status(200).send('OK');
  } catch (err) {
    console.error('Webhook verification failed:', err.message);
    res.status(400).send('Invalid signature');
  }
});

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.

Webhook payload fields

callConversationEnded

callConversationInsightsGenerated

callDtmfReceived

callMachineDetectionEnded

callMachineGreetingEnded

callMachinePremiumDetectionEnded

callMachinePremiumGreetingEnded

callReferCompleted

callReferFailed

callReferStarted

callSiprecFailed

callSiprecStarted

callSiprecStopped