Remove leading first zero on the billing phone number after registration in WooCommerce on your child site.
Snippet Type
Execute on Child Sites
Snippet
function removezero( $user_id ) {
if (isset($_POST['billing_phone'])) {
update_user_meta( $user_id, 'billing_phone', $_POST['billing_phone'] = preg_replace('/^0/', '', $_POST['billing_phone']));
}
}