GravityForms Authorize.net Add-on Transaction Data Filter

add_filter('gform_authorizenet_before_single_payment','my_anet_custom_fields', 10, 2);
function my_anet_custom_fields($transaction, $form_data) {

        # GET DATA FROM FORM INPUT
        $form_data["phone"] = rgpost('input_3');

        # ADD DATA TO TRANSACTION OBJECT
        $transaction->phone = $form_data["phone"];

        return $transaction;
}