First you can browse your existing numbers.
If you have no spare numbers you can buy one.
You can purchase a number using the Vonage CLI. The following command purchases an available number in the US. Specify an alternate two-character country code to purchase a number in another country.
$ vonage numbers:search US $ vonage numbers:buy 15555555555 US
Connect to a WebSocketConnect an inbound call to a WebSocket with the Voice API