/telnyx-fax-javascript

name: telnyx-fax-javascript
description: >-
  Send and receive faxes programmatically. Manage fax applications and media.
  This skill provides JavaScript SDK examples.
metadata:
  author: telnyx
  product: fax
  language: javascript
  generated_by: telnyx-openapi-pipeline

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

Telnyx Fax - 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
  publicKey: process.env['TELNYX_PUBLIC_KEY'], // Required for client.webhooks.unwrap() (webhook verification)
});

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, then retry the request (bounded exponential backoff)
    const retryAfter = err.headers?.['retry-after'] || 1;
    await new Promise(r => setTimeout(r, retryAfter * 1000));
    // ...retry the call here (give up after a few attempts)
  } 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');
    }
  }
  throw err; // Re-throw: a failed request must never look like success to the caller
}

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).

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.

List all Fax Applications

This endpoint returns a list of your Fax Applications inside the 'data' attribute of the response. You can adjust which applications are listed by using filters. Fax Applications are used to configure how you send and receive faxes using the Programmable Fax API with Telnyx.

`GET /fax_applications`

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

Returns: `active` (boolean), `anchorsite_override` (enum: Latency, Chicago, IL, Ashburn, VA, San Jose, CA, Sydney, Australia, Amsterdam, Netherlands, London, UK, Toronto, Canada, Vancouver, Canada, Frankfurt, Germany), `application_name` (string), `created_at` (string), `id` (string), `inbound` (object), `outbound` (object), `record_type` (string), `tags` (array[string]), `updated_at` (string), `webhook_event_failover_url` (uri), `webhook_event_url` (uri), `webhook_timeout_secs` (integer | null)

Creates a Fax Application

Creates a new Fax Application based on the parameters sent in the request. The application name and webhook URL are required. Once created, you can assign phone numbers to your application using the `/phone_numbers` endpoint.

`POST /fax_applications` — Required: `application_name`, `webhook_event_url`

Optional: `active` (boolean), `anchorsite_override` (enum: Latency, Chicago, IL, Ashburn, VA, San Jose, CA, Sydney, Australia, Amsterdam, Netherlands, London, UK, Toronto, Canada, Vancouver, Canada, Frankfurt, Germany), `inbound` (object), `outbound` (object), `tags` (array[string]), `webhook_event_failover_url` (uri), `webhook_timeout_secs` (integer | null)

const faxApplication = await client.faxApplications.create({
  application_name: 'fax-router',
  webhook_event_url: 'https://example.com',
});

console.log(faxApplication.data);

Returns: `active` (boolean), `anchorsite_override` (enum: Latency, Chicago, IL, Ashburn, VA, San Jose, CA, Sydney, Australia, Amsterdam, Netherlands, London, UK, Toronto, Canada, Vancouver, Canada, Frankfurt, Germany), `application_name` (string), `created_at` (string), `id` (string), `inbound` (object), `outbound` (object), `record_type` (string), `tags` (array[string]), `updated_at` (string), `webhook_event_failover_url` (uri), `webhook_event_url` (uri), `webhook_timeout_secs` (integer | null)

Retrieve a Fax Application

Return the details of an existing Fax Application inside the 'data' attribute of the response.

`GET /fax_applications/{id}`

const faxApplication = await client.faxApplications.retrieve('1293384261075731499');

console.log(faxApplication.data);

Returns: `active` (boolean), `anchorsite_override` (enum: Latency, Chicago, IL, Ashburn, VA, San Jose, CA, Sydney, Australia, Amsterdam, Netherlands, London, UK, Toronto, Canada, Vancouver, Canada, Frankfurt, Germany), `application_name` (string), `created_at` (string), `id` (string), `inbound` (object), `outbound` (object), `record_type` (string), `tags` (array[string]), `updated_at` (string), `webhook_event_failover_url` (uri), `webhook_event_url` (uri), `webhook_timeout_secs` (integer | null)

Update a Fax Application

Updates settings of an existing Fax Application based on the parameters of the request.

`PATCH /fax_applications/{id}` — Required: `application_name`, `webhook_event_url`

Optional: `active` (boolean), `anchorsite_override` (enum: Latency, Chicago, IL, Ashburn, VA, San Jose, CA, Sydney, Australia, Amsterdam, Netherlands, London, UK, Toronto, Canada, Vancouver, Canada, Frankfu