It comes in handy when you want to reach out to your customers by calling to their mobile phones and landlines. There is a method called callPSTN that allows you to place such calls: you have to specify a target number (who you’re going call to) and a source number (who is calling).
While technically no source phone is involved in calling a target phone number from the cloud, some phone number should be displayed to the callee so that a person can call back. You can specify a number rented from Voximplant or any number you own after confirming it in the Voximplant control panel.
Test numbers aren’t allowed to operate in that way.
The example of how an outbound call could be implemented in a JS scenario: