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How HerCare Voice Works Under the Hood

System Architecture Overview

A complete breakdown of the technical architecture powering Maya — the 24/7 AI voice receptionist. Below is the workflow representing real-time voice call interaction and post-call logging.

Architecture Diagram

Live Call Flow
Patient Call
→
Retell AI(Voice Platform)
→
GPT-4.1 Mini(AI Brain)
→
Cal.com(Availability Check)
→
Google Calendar(Appointment Booked)
Call Ends
Post-Call Automation
Retell AI
→
call_analyzed Webhook
→
n8n(Automation)
→
Google Sheets(Data Logged)

Component Breakdown

Underlying Tech Stack Details

Maya is powered by an orchestration of state-of-the-art Voice AI tools, low-latency LLMs, calendar booking, and backend webhook handlers.

Component 01

Retell AI

The voice platform. Handles receiving calls, speech-to-text, running the AI, text-to-speech, and post-call data extraction. It is the central hub connecting all other tools.

Component 02

GPT-4.1 Mini

The AI language model powering Maya's conversation. Chosen for low latency — faster responses than the full GPT-4.1, which is critical in a live phone call.

Component 03

Cartesia Hailey

The voice Maya uses. Switched from the default Retell AI voice to eliminate audio buffering and latency issues.

Component 04

Cal.com

Real-time appointment scheduling. The agent calls two Cal.com functions during the call — Check Availability and Book Appointment — both wired as explicit flow nodes in Retell AI.

Component 05

Google Calendar

Final destination for all booked appointments. Connected to Cal.com — bookings appear here automatically.

Component 06

n8n

Post-call automation tool. Listens for the call_analyzed webhook event from Retell AI and routes patient data to Google Sheets.

Component 07

Google Sheets

Automatic call log. Every call creates a new row with 7 fields: patient_first_name, patient_last_name, date_of_birth, service_type, appointment_date, appointment_time, appointment_booked.

Call Flow Steps

Retell AI Node Canvas Flow

Maya's conversational flow is structured inside Retell AI's visual canvas across 6 sequential steps:

  • 1. Welcome Node: Greets the caller and introduces herself as Maya, the digital receptionist for HerCare.
  • 2. Conversation Node: Asks questions to gather critical patient details (first/last name, DOB, requested service).
  • 3. Check Availability Node: Triggers Cal.com API call to search for real-time scheduling slots in the clinic's calendar.
  • 4. Book Appointment Node: Books the selected slot via Cal.com, sending confirmation backend events.
  • 5. Closing Message Node: Confirms the booking details with the caller and thanks them for choosing HerCare.
  • 6. End Call: Safely disconnects the call and triggers post-call processing.

Experience Maya Live

Call the receptionist live right now to test the real-time reservation capabilities, or visit the live simulation site.

Call Maya Live View Case Study

HerCare Voice — 24/7 AI Voice Receptionist. Built by Rani Neog Adhikary under BuildSmart AI.

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