At a business, a secretary, almost always a woman, would answer the phone for all calls. There were no direct lines into anyone. If you were in she would transfer the call to your office. If you were out she would use this pad to take messages. When you came back in to the office you would always stop at the front desk and you would be handed your messages.
In small offices in particular, separate voicemail for everyone is less practical than a person taking messages. This is reminiscent of people making fun of how ancient fax machines are when they’re still in common usage in the medical field.
I have to fix a fax machine in ICU tomorrow morning 😭