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Systemartis
// case · 2026

How an AI voice agent answers every call a French garage used to miss

An AI voice agent that answers an independent French garage's phone in natural French, checks live calendar availability, and books the appointment during the call, with RGPD (GDPR) compliance built into the data layer.

Built for an independent French garage. Identifying details anonymized at the client's request.

MacBook on a desk showing the AI voice agent's call log, with call outcomes and booking summaries in French
  • €7K
    Missed-call revenue at stake
    ~3 missed calls/day × €250 job
  • 24/7
    Inbound calls answered
    nights, lunch, after-hours
  • 0
    Callbacks to book
    booked live, during the call
// challenge

Why a busy garage keeps missing calls

Phones don't stop ringing because the bays are full. An independent auto repair garage near Toulouse was losing about three calls a day to lunch breaks, early mornings, and after-hours, each one heading to the competitor. At around €250 a job, that is close to €7,000 a month. A full-time receptionist never paid for itself.

// approach

How the AI voice agent answers and books in French

We built an AI voice agent that answers every inbound call in natural French. It works out what the caller needs, checks real availability, and books before hanging up. No callbacks. It speaks from the garage's own services, prices, and hours, so it sounds like the shop, not a bot. One platform runs many garages, each kept isolated.

// architecture

The architecture behind real-time phone booking

Retell AI runs the conversation with a cascading LLM and ElevenLabs voices; Twilio carries the call over SIP and sends SMS confirmations. Availability comes from intersecting working hours, PostgreSQL appointments, and Google Calendar, in Europe/Paris. A database-level exclusion constraint makes double-booking impossible, not unlikely. Provider credentials are encrypted with AES-256-GCM, and every Retell webhook is HMAC-verified.

stack
  • Retell AI
  • Twilio
  • Google Calendar API
  • PostgreSQL + Drizzle
  • Hono + HTMX
// outcome

What changed: every call answered, booked in-call

The garage now answers every call and books into the calendar while the caller is on the line. RGPD was a constraint from the start: transcripts auto-purge after 30 days, and callers can be deleted by phone number. Call and booking numbers are being instrumented now; the first that matters is simple: calls that rang out now get answered.

// other cases

Other systems we've shipped.

// ready when you are

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