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Callback for Inbound Fax


The SignalWire Fax API allows you to have full event monitoring through the usage of status callbacks. The below example will demonstrate how to configure your SIgnalWire phone number through XML bins to receive a fax and alert your own server of fax events that are occurring in your SignalWire Space.

How To Run the Application

Configuring Your Number

In order to achieve this via XML, you will have to navigate to the LaML section on the left side of your SignalWire Dashboard and select + New to create a new LaML Bin.

We then need to enter in the XML language for receiving a fax into our LaML Bin. The below code is taken from the Receive a Fax in Compatibility XML example .

<?xml version="1.0" encoding="UTF-8"?>
<Receive action="https://YOUR_URL_EXPECTING_A_CALLBACK."/>

Enter in the above XML and your page should now look something like this below.

Lastly, we must associate a phone number to the webhook created via a LaML bin. To do this, we must navigate to Phone Numbers on the left side of your SIgnalWire Dashboard. Click on a number and select Edit Settings

Note that we set 'Accept Incoming Calls As:' Fax, We 'Handle Faxes Using:' LaML Webhooks, and then paste in our LaML Bin URL.

Testing your Configured Fax Number

Congratulations, your phone number is now configured! It is time to test your phone number by Sending a Fax to your fax receiving phone numer.

Once your fax has been received, you should receive a payload to your actionURL that looks similar to the one below. Feel free to read up more on Request Parameters and Additional Callback Parameters for more information on the data being sent.

Additional Information on Callback Authentication

When using SignalWire for Inbound Fax, the callback can be made secure. Unfortunately, there is no set list of IP addresses that SignalWire can provide as they change frequently. That being said, there are a couple of ways to work around this.

As an alternative method, callbacks support basic authentication as well, for example, You can also view and allow SignalWire IPs in real-time by running a specific script. However, as stated before, they change frequently, so keep your eye on them.

Wrap Up

This mini-guide walked through how you can configure your SignalWire phone number to receive incoming faxes, and also opened the door to a variety of other monitoring methods through status callbacks. Each significant event that occurs will be relayed back to your actionURL so that you can keep an eye on your traffic without having to keep an eye on your SignalWire dashboard.

Additional Resources:

Sign Up Here

If you would like to test this example out, you can create a SignalWire account and space here.

Please feel free to reach out to us on our Community Slack or create a Support ticket if you need guidance!