Fax

Fax Overview

View as Markdown

Fax cXML is a set of actions defined in an XML document you can use to tell SignalWire what to do when you receive an incoming fax.

Overview

When a fax is sent to one of your SignalWire phone numbers, SignalWire looks up the Fax cXML document from the URL you configured, and reads the instructions you provided to determine what to do.

Fax cXML allows you to control what SignalWire will do when you receive an incoming fax.

Request

SignalWire makes an HTTP request to your configured endpoint just like a regular web form submission (POST) or page load (GET). The request includes contextual information about the fax, allowing you to respond dynamically and fluidly to the fax to meet the needs of your application.

You can configure the endpoint URL and HTTP Method in your phone number settings panel on your SignalWire Dashboard, or via the REST API.

Request parameters

SignalWire sends the following parameters, as either URL query parameters or POST parameters, to your endpoint when it receives a fax:

AccountSid
string

The account that the fax was sent from.

ApiVersion
string

The version of the SignalWire API.

FaxSid
string

A unique identifier for the fax.

From
string

The number or SIP URI the fax was sent from.

To
string

The number or SIP URI the fax will be sent to.

Responding to SignalWire

An example of a cXML document that receives an incoming fax:

1<?xml version="1.0" encoding="UTF-8"?>
2<Response>
3  <Receive action="/fax/received"/>
4</Response>

When a fax comes into one of your SignalWire phone numbers, SignalWire makes an HTTP request to the URL endpoint you configured for that number. Your response to that request instructs SignalWire on what to do next.

Responses to the HTTP request are in SignalWire cXML. SignalWire starts at the top of your XML document and executes your commands in order, from top to bottom.

cXML verbs and their attributes are case-sensitive, so using <receive> instead of <Receive> will result in an error.

StatusCallback when sending a fax

When sending a fax you can specify a StatusCallback URL. If you do so, your specified URL will receive POST requests with the following parameters:

ErrorCode
string

The error code provides more information on a failed fax.

ErrorMessage
string

The message explaining the reason for fax failure.

FaxStatus
string

The status of the fax.

MediaSid
string

The SID that uniquely identifies the fax media.

MediaUrl
string

The media URL to request to retrieve incoming media.

NumPages
integer

The number of pages received from a successful fax.

OriginalMediaUrl
string

The original URL passed when a fax is sent.

RemoteStationId
string

The transmitting subscriber identification (TSID) reported by the fax machine that sent in the fax.

Instructions

The following instructions are used to manage faxes:

Receive

Receive an incoming fax.

Reject

Reject an incoming fax.