Securing Callback for Inbound Fax with SignalWire Compatible XML

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.

The first method is to add customer parameters to the callback URL so that those parameters can be sent alongside the SignalWire parameter. This method can restrict unknown requests. Below, you will see how this can be achieved:

<Receive mediaType="Iimage/tiff" storeMedia="true" method="POST" action="HTTP://<IP:PORT>/inbound-fax?token=RandomString"/>;

As an alternative method, callbacks support basic authentication as well, for example, https://user:[email protected]. 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.

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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!

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