WooCommerce - make phone number not required on checkout page

woocommerce-phone-number-not-required.php

// make phone number at checkout not required
add_filter( 'woocommerce_billing_fields', 'jwd_filter_phone' );
function jwd_filter_phone( $address_fields ) {
	$address_fields['billing_phone']['required'] = false;
	return $address_fields;
}