The signs
You already forward the night line to a personal cell. Callers mention they tried yesterday and got voicemail. New jobs, new patients, or new reservations show up as next-day emails instead of same-night conversations. Staff open the morning by returning a stack of calls. A storm, a holiday, or a lunch break creates a hole you can see in the missed-call log.
Two more are easy to miss. The work itself happens after hours, as it does for towing, plumbing, pediatrics, and restaurants. Or the caller is choosing between you and a competitor who simply answered.
What overnight coverage should actually do
It should not pretend the office is open. It should say the office is closed, answer the safe questions, and sort the rest. A pool leak can be a message with a four-hour window. A child who will not wake is a direction to call emergency services. A parts question can wait for morning with the vehicle details already written down.
Around the clock does not mean a person sits awake. It means the line is answered, the rule is followed, and the human sees a note instead of a blank missed call.