Which of these is not generally a good practice for telephone use? only names and callback numbers are left on voicemail or answering machines -- or with the person that takes the message -- if someone cannot be reached directly. when discussing confidential information on the phone, the other person's identity is confirmed before proceeding with the conversation. using voicemail systems and answering machines that do not require a password or pin for access. whenever possible, telephone conversations involving sensitive information are conducted in non-public areas, where they cannot be overheard.