PHP: Calling MySQL Stored Procedure with Both INPUT AND OUTPUT Parameters (NOT "INOUT")

$procInput1 = 123;
$procInput2 = 456;
$procInput3 = 789;

$mysqli = mysqli_connect();

$call = mysqli_prepare($mysqli, 'CALL test_proc(?, ?, ?, @sum, @product, @average)');
mysqli_stmt_bind_param($call, 'iii', $procInput1, $procInput2, $procInput3);
mysqli_stmt_execute($call);

$select = mysqli_query($mysqli, 'SELECT @sum, @product, @average');
$result = mysqli_fetch_assoc($select);
$procOutput_sum     = $result['@sum'];
$procOutput_product = $result['@product'];
$procOutput_average = $result['@average'];

$procInput1 = 123;
$procInput2 = 456;
$procInput3 = 789;

$mysqli = new mysqli();

$call = $mysqli->prepare('CALL test_proc(?, ?, ?, @sum, @product, @average)');
$call->bind_param('iii', $procInput1, $procInput2, $procInput3);
$call->execute();

$select = $mysqli->query('SELECT @sum, @product, @average');
$result = $select->fetch_assoc();
$procOutput_sum     = $result['@sum'];
$procOutput_product = $result['@product'];
$procOutput_average = $result['@average'];

 DB::select('call SP_fci_cb_emp_comp_salary_revision_add(?,?,?,@,@)',
                        [
                            $my_compensation['detail']['employee_master_id'],
                            Carbon::createFromFormat('d/m/Y', $salary_revised_result['detail']->effective_date)->format('Y-m-d'),
                            $request->user_id
                        ]);