private async Task<Call> InitiateOutboundCallAsyncInternal(CallOptions options)
{
Require.Argument("From", options.From);
Require.Argument("To", options.To);
var request = new RestRequest();
request.Method = Method.POST;
request.Resource = "Accounts/{AccountSid}/Calls.json";
AddCallOptions(options, request);
var result = await ExecuteAsync(request, typeof(Call));
return (Call)result;
}