Pos NTLM Auth

        private static ProcessRequestResponseProcessRequestResult SendRequest(ProcessRequestRequest posRequest, UserModel user)
        {
            using (var pos = new POSProcessingSoapClient("endpoint_configuration_name"))
            {
                pos.ClientCredentials.Windows.ClientCredential.UserName = user.Name;
                pos.ClientCredentials.Windows.ClientCredential.Domain = user.Domain;
                pos.ClientCredentials.Windows.ClientCredential.Password = user.Password;

                return pos.ProcessRequest(posRequest, "org_name");
            }
        }