Telnyx Voice - JavaScript

Installation

npm install telnyx

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

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 response = await client.calls.dial({
    connection_id: '7267xxxxxxxxxxxxxx',
    from: '+18005550101',
    to: '+18005550100',
  });
} catch (err) {
  if (err instanceof Telnyx.APIConnectionError) {
    console.error('Network error — check connectivity and retry');
  } else if (err instanceof Telnyx.RateLimitError) {
    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

403

404

422

429

Important Notes

• Phone numbers must be in E.164 format (e.g.,

  +13125550001

  ). Include the

  +

  prefix and country code. No spaces, dashes, or parentheses.
• Pagination: List methods return an auto-paginating iterator. Use

  for await (const item of result) { ... }

  to iterate through all pages automatically.

Operational Caveats

• Call Control is event-driven. After

  dial()

  or an inbound webhook, issue follow-up commands from webhook handlers using the

  call_control_id

  in the event payload.
• Outbound and inbound flows are different: outbound calls start with

  dial()

  , while inbound calls must be answered from the incoming webhook before other commands run.
• A publicly reachable webhook endpoint is required for real call control. Without it, calls may connect but your application cannot drive the live call state.

Reference Use Rules

Do not invent Telnyx parameters, enums, response fields, or webhook fields.

• If the parameter, enum, or response field you need is not shown inline in this skill, read references/api-details.md before writing code.
• Before using any operation in

  ## Additional Operations

  , read the optional-parameters section and the response-schemas section.
• Before reading or matching webhook fields beyond the inline examples, read the webhook payload reference.

Core Tasks

Dial an outbound call

Primary voice entrypoint. Agents need the async call-control identifiers returned here.

client.calls.dial()

POST /calls

to

from

from

connectionId

timeoutSecs

billingGroupId

clientState

const response = await client.calls.dial({
  connection_id: '7267xxxxxxxxxxxxxx',
  from: '+18005550101',
  to: '+18005550100',
});

console.log(response.data);

Primary response fields:

• response.data.callControlId

• response.data.callLegId

• response.data.callSessionId

• response.data.isAlive

• response.data.recordingId

• response.data.callDuration

Answer an inbound call

Primary inbound call-control command.

client.calls.actions.answer()

POST /calls/{call_control_id}/actions/answer

callControlId

billingGroupId

clientState

webhookUrl

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

console.log(response.data);

Primary response fields:

• response.data.result

• response.data.recordingId

Transfer a live call

Common post-answer control path with downstream webhook implications.

client.calls.actions.transfer()

POST /calls/{call_control_id}/actions/transfer

to

callControlId

timeoutSecs

clientState

webhookUrl

const response = await client.calls.actions.transfer('call_control_id', {
  to: '+18005550100',
});

console.log(response.data);

Primary response fields:

• response.data.result

Webhook Verification

Telnyx signs webhooks with Ed25519. Each request includes

telnyx-signature-ed25519

telnyx-timestamp

// 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');
  }
});

Webhooks

These webhook payload fields are inline because they are part of the primary integration path.

Call Answered

data.record_type

data.event_type

data.id

data.occurred_at

data.payload.call_control_id

data.payload.connection_id

data.payload.call_leg_id

data.payload.call_session_id

Call Hangup

data.record_type

data.event_type

data.id

data.occurred_at

data.payload.call_control_id

data.payload.connection_id

data.payload.call_leg_id

data.payload.call_session_id

Call Initiated

data.record_type

data.event_type

data.id

data.occurred_at

data.payload.call_control_id

data.payload.connection_id

data.payload.connection_codecs

data.payload.offered_codecs

If you need webhook fields that are not listed inline here, read the webhook payload reference before writing the handler.

Important Supporting Operations

Use these when the core tasks above are close to your flow, but you need a common variation or follow-up step.

Hangup call

End a live call from your webhook-driven control flow.

client.calls.actions.hangup()

POST /calls/{call_control_id}/actions/hangup

callControlId

clientState

commandId

customHeaders

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

console.log(response.data);

Primary response fields:

• response.data.result

Bridge calls

Trigger a follow-up action in an existing workflow rather than creating a new top-level resource.

client.calls.actions.bridge()

POST /calls/{call_control_id}/actions/bridge

callControlId

callControlId

clientState

commandId

videoRoomId

const response = await client.calls.actions.bridge('call_control_id', {
  call_control_id_to_bridge_with: 'v3:MdI91X4lWFEs7IgbBEOT9M4AigoY08M0WWZFISt1Yw2axZ_IiE4pqg',
});

console.log(response.data);

Primary response fields:

• response.data.result

Reject a call

Trigger a follow-up action in an existing workflow rather than creating a new top-level resource.

client.calls.actions.reject()

POST /calls/{call_control_id}/actions/reject

cause

callControlId

clientState

commandId

const response = await client.calls.actions.reject('call_control_id', { cause: 'USER_BUSY' });

console.log(response.data);

Primary response fields:

• response.data.result

Retrieve a call status

Fetch the current state before updating, deleting, or making control-flow decisions.

client.calls.retrieveStatus()

GET /calls/{call_control_id}

callControlId

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

console.log(response.data);

Primary response fields:

• response.data.callControlId

• response.data.callDuration

• response.data.callLegId

• response.data.callSessionId

• response.data.clientState

• response.data.endTime

List all active calls for given connection

Fetch the current state before updating, deleting, or making control-flow decisions.

client.connections.listActiveCalls()

GET /connections/{connection_id}/active_calls

connectionId

page

// Automatically fetches more pages as needed.
for await (const connectionListActiveCallsResponse of client.connections.listActiveCalls(
  '1293384261075731461',
)) {
  console.log(connectionListActiveCallsResponse.call_control_id);
}

Response wrapper:

• items:

  connectionListActiveCallsResponse.data

• pagination:

  connectionListActiveCallsResponse.meta

Primary item fields:

• callControlId

• callDuration

• callLegId

• callSessionId

• clientState

• recordType

List call control applications

Inspect available resources or choose an existing resource before mutating it.

client.callControlApplications.list()

GET /call_control_applications

sort

filter

page

// Automatically fetches more pages as needed.
for await (const callControlApplication of client.callControlApplications.list()) {
  console.log(callControlApplication.id);
}

Response wrapper:

• items:

  callControlApplication.data

• pagination:

  callControlApplication.meta

Primary item fields:

• id

• createdAt

• updatedAt

• active

• anchorsiteOverride

• applicationName

Additional Operations

Use the core tasks above first. The operations below are indexed here with exact SDK methods and required params; use references/api-details.md for full optional params, response schemas, and lower-frequency webhook payloads. Before using any operation below, read the optional-parameters section and the response-schemas section so you do not guess missing fields.

client.callControlApplications.create()

POST /call_control_applications

applicationName

webhookEventUrl

client.callControlApplications.retrieve()

GET /call_control_applications/{id}

id

client.callControlApplications.update()

PATCH /call_control_applications/{id}

applicationName

webhookEventUrl

id

client.callControlApplications.delete()

DELETE /call_control_applications/{id}

id

client.calls.actions.refer()

POST /calls/{call_control_id}/actions/refer

sipAddress

callControlId

client.calls.actions.sendSipInfo()

POST /calls/{call_control_id}/actions/send_sip_info

contentType

body

callControlId

Other Webhook Events

data.event_type

callBridged

call.bridged

For exhaustive optional parameters, full response schemas, and complete webhook payloads, see references/api-details.md.