static private async Task call_ringout()
{
    RestClient rc = new RestClient("client_id", "client_secret", false);
    await rc.Authorize("rc_jwt");
    var parameters = new MakeRingOutRequest();
    parameters.from = new MakeRingOutCallerInfoRequestFrom { phoneNumber = "13443334444" };
    parameters.to = new MakeRingOutCallerInfoRequestTo { phoneNumber = "13453443434" };
    parameters.playPrompt = true;

    var resp = await rc.Restapi().Account().Extension().RingOut().Post(parameters);
    Console.WriteLine("Call Placed. Call status: " + resp.status.callStatus);
}