It is safer than speaking your number over the phone because of the encryption used. If you are concerned about ordering online please follow this link to read about Yahoo's secure server that hosts our site and processes our orders. Because secure mode can slow down the site, you will see the security icon only in the order form.
Since we started taking orders online in 1998 we've never had a card number lost or stolen. Additionally, Yahoo! purges your credit card number from the online system after 30 days. Rest assured that every precaution is taken to keep your information safe and confidential.