add validation code for phone number in checkout page

Hello, before im making changes, can you tell me please if this code is good and where to put it ?

add_filter(‘woocommerce_process_registration_errors’,’custom_validate_billing_phone’,10, 4 )
add_action( “woocommerce_after_save_address_validation”,’custom_validate_billing_phone’,1,2);
add_action(‘woocommerce_checkout_process’, ‘custom_validate_billing_phone’);
function custom_validate_billing_phone() {
$is_correct = preg_match(‘/^05[0-9]{8}$/’, $_POST[‘billing_phone’]);
if ( $_POST[‘billing_phone’] && !$is_correct) {
wc_add_notice( __( ‘The Phone field should be start 05 and 10 digits.’ ), ‘error’ );
}
}