Modify woocommerce billing phone

function change_billing_phone_number (null, $order) {
  $billing_phone = $order->get_billing_phone();
  $billing_phone = str_replace('+', '00', $billing_phone);
  $order->set_billing_phone($billing_phone);
  $order_id = $order->save();

  return $order_id;
}
add_filter( 'woocommerce_create_order', 'change_billing_phone_number', 10, 2);