How to Add Country Code in Woocommerce Billing Phone Field

// Add country calling code prefix in woocommerce billing phone
add_action( 'wp_footer', 'wpsh_add_callback' );
function wpsh_add_callback(){
    ?>
    <script type="text/javascript">
        ( function( $ ) {
            $( document.body ).on( 'updated_checkout', function(data) {
                var ajax_url = "<?php echo admin_url('admin-ajax.php'); ?>",
                country_code = $('#billing_country').val();

                var ajax_data = {
                    action: 'append_country_prefix_in_billing_phone',
                    country_code: country_code
                };

                $.post( ajax_url, ajax_data, function( response ) {
                    $('#billing_phone').val(response);
                });
            } );
        } )( jQuery );
    </script>
    <?php
}

add_action( 'wp_ajax_nopriv_append_country_prefix_in_billing_phone', 'wpsh_add_phone_prefix' );
add_action( 'wp_ajax_append_country_prefix_in_billing_phone', 'wpsh_add_phone_prefix' );
function wpsh_add_phone_prefix() {
    $calling_code = '';
    $country_code = isset( $_POST['country_code'] ) ? sanitize_text_field( $_POST['country_code'] ) : '';
    if( $country_code ){
        $calling_code = WC()->countries->get_country_calling_code( $country_code );
        $calling_code = is_array( $calling_code ) ? $calling_code[0] : $calling_code;
    }
    echo $calling_code;
    die();
}
// Phone number shoud be at least 6 digits long. This avoids the problem with not adding a phone number
add_action('woocommerce_checkout_process', 'wpsh_validate_phone');
function wpsh_validate_phone() {
    if (isset($_POST['billing_phone'])) {
        $phone = strlen(preg_replace('/[^0-9]/', '', $_POST['billing_phone']));
        if ($phone < 6) {
            wc_add_notice( __( '<strong>Billing Phone</strong> must be at least 6 digits long.' ), 'error' );
        }
    }
}