Case study · Cross-vertical · Voice agent · 75 days
After-hours coverage without an after-hours team.
A service business was losing weekend bookings to voicemail. A voice agent now answers the calls a human would otherwise miss — and quietly hands off the ones that need real judgment.
Chapter 01 · The problem
Saturday mornings were the busiest hour, and nobody was on the phone.
A multi-site allied health practice had a familiar gap. The clinics opened at eight on weekdays. The phone, on Saturdays, did not. Patients calling in on a weekend — most of them existing patients chasing a new appointment — went to voicemail. Roughly a third never called back. The Service Lead had been recovering some of them through Monday morning callbacks, but the slot had usually filled by then. The pattern was easy to see in the booking system; harder to see was the quiet revenue walking out of the funnel every weekend.
~110 weekend calls a month
Chapter 02 · The approach
We did not staff the weekend. We answered the call that was easy to answer.
The fix was a voice agent that picked up the after-hours line and recognised the difference between a booking call and a clinical one. For booking calls, it offered the next three available slots from the practice management system, confirmed by SMS, and ended the call inside two minutes. For anything that sounded clinical or unusual — pain levels, post-op questions, anything outside its scope — it took a callback request and routed it to the duty practitioner’s queue for Monday morning. The agent never tried to give a clinical answer. That line was bright on purpose.
What we built
A Twilio + Vapi voice agent fronted by ElevenLabs voice synthesis for the spoken response, with Anthropic Claude handling intent recognition and slot selection. n8n integrates the booking workflow and the SMS confirmation. The Hermes orchestrator coordinates the agent, the handoff queue, and the post-call transcript redaction.
Build time · 21 days · pilot phase · followed by 9 weeks of iteration with the Service Lead and the duty-roster practitioners.
Chapter 03 · The outcome
Three numbers the Saturday roster felt before the report ran.
- 0%
of after-hours calls answered by the agent — measured across a 90-day rolling window post-pilot.
- 0 s
mean handoff time to the duty practitioner queue when the call moved outside the agent’s scope.
- +0%
callback recovery on weekend bookings — measured against the prior quarter Monday-morning catch-up rate.
Numbers verified by the Service Lead against the practice-management booking exports. Anonymised under our standard case-study disclosure: vertical and outcome are real; practice name, locations, and PMS-specific identifiers are not.
Chapter 04 · What we learned
The agent was easy. The boundary was the hard part.
The voice pipeline itself took 21 days. The nine weeks that followed were spent on a single line: when does the agent step out of the conversation. We logged every call where the patient drifted from booking into clinical territory and watched the agent’s response in review. Some were obvious — the agent should hand off. Some were tone calls — the patient was venting, not asking — and we tuned a handoff phrase the practitioners actually liked the sound of when they heard it on Monday.
The lesson was about the boundary, not the booking. The agent never needed to be smarter at clinical questions; it needed to be quicker at recognising it was not the right voice for the call. Once the handoff felt warm, the Service Lead stopped reviewing the transcripts daily and started reviewing them weekly.
Settled handoff rate · ~6% handoff rate
Chapter 05 · In the client’s words
The agent is not pretending to be a clinician. It is just picking up the phone on a Saturday morning. That is the bit our patients were missing.
Service Lead · Multi-site allied health practice · AU (anonymised at the client’s request)
Curious whether your service has the same after-hours gap?
A free 45-minute audit. We look at your call volume, your booking system, and where the after-hours funnel is leaking. You leave with a one-page memo, whether we’d be a fit or not.