When not getting through to a business on the phone, hanging up and hitting redial instead of talking to the voicemail 5

Oh yes, even though we set up a voice mail at work for when we are either on the other line or helping the doctor, some people rather than leave a message, just keep hitting redial. Every time call waiting beeps in we lose close to a minute of the other person's conversation...the more one hits redial and beeps in on us, the longer our conversation becomes because the person I am speaking with needs to continue to repeat what they first said. A friend of mine was trying to get through to a business one day that did not have voice mail...he kept redialing. I finally told him that the person he was trying to reach will probably need more than half a minute to be free to help him.