Build a Voice Appointment Reminder Bot: AI Calls That Confirm, Reschedule, or Cancel

Your Backend
    │
    ├── POST /calls (initiate outbound call)
    │       │
    │       ▼
    │   VoIPBin ──── calls patient's phone
    │       │
    │       ├── STT: patient speech → text
    │       ├── sends text to your AI
    │       ├── TTS: AI response → audio
    │       │
    │       └── POST /webhook (call events)
    │               │
    └───────────────┘
                    ▼
              Update your DB

curl -s -X POST https://api.voipbin.net/v1.0/auth/signup \
  -H "Content-Type: application/json" \
  -d '{"username": "yourname", "password": "yourpass"}'

from flask import Flask, request, jsonify
import openai

app = Flask(__name__)
client = openai.OpenAI()

sessions = {}  # conversation_id -> history

@app.route("/ai", methods=["POST"])
def handle_voice_turn():
    data = request.json
    call_id = data.get("call_id")
    user_text = data.get("text", "")

    if call_id not in sessions:
        sessions[call_id] = [
            {
                "role": "system",
                "content": (
                    "You are a scheduling assistant for Maple Dental Clinic. "
                    "You're calling to confirm tomorrow's appointment. "
                    "Be concise — this is a phone call. "
                    "Ask if they can confirm, reschedule, or if they need to cancel. "
                    "When they decide, say: 'Great, I've noted that. Have a good day!' "
                    "and end the call."
                )
            }
        ]

    sessions[call_id].append({"role": "user", "content": user_text})

    response = client.chat.completions.create(
        model="gpt-4o",
        messages=sessions[call_id]
    )

    reply = response.choices[0].message.content
    sessions[call_id].append({"role": "assistant", "content": reply})

    # Signal call end when AI wraps up
    should_end = "have a good day" in reply.lower()

    return jsonify({
        "text": reply,
        "end_call": should_end
    })

if __name__ == "__main__":
    app.run(port=8080)

@app.route("/webhook", methods=["POST"])
def call_webhook():
    event = request.json
    call_id = event.get("call_id")
    event_type = event.get("type")

    if event_type == "call.ended":
        # Extract last user intent from session history
        history = sessions.get(call_id, [])
        last_user_msg = next(
            (m["content"] for m in reversed(history) if m["role"] == "user"),
            ""
        ).lower()

        if "cancel" in last_user_msg:
            update_appointment(call_id, status="cancelled")
        elif "reschedule" in last_user_msg or "change" in last_user_msg:
            update_appointment(call_id, status="reschedule_requested")
        else:
            update_appointment(call_id, status="confirmed")

        # Clean up session
        sessions.pop(call_id, None)

    return jsonify({"ok": True})

def update_appointment(call_id, status):
    # Your DB update logic here
    print(f"[{call_id}] Appointment status: {status}")

import httpx

VOIPBIN_TOKEN = "your-access-token"

def call_patient(patient_phone: str, call_id: str):
    payload = {
        "source": "+15551234567",   # your VoIPBin number
        "destination": patient_phone,
        "ai_url": "https://yourserver.com/ai",
        "webhook_url": "https://yourserver.com/webhook",
        "metadata": {"call_id": call_id}
    }

    res = httpx.post(
        "https://api.voipbin.net/v1.0/calls",
        json=payload,
        headers={
            "Authorization": f"Bearer {VOIPBIN_TOKEN}",
            "Content-Type": "application/json"
        }
    )
    return res.json()

# Example: trigger reminder for tomorrow's appointments
for appt in get_tomorrows_appointments():
    call_patient(appt["phone"], appt["id"])

# crontab -e
0 10 * * * /usr/bin/python3 /app/trigger_reminders.py >> /var/log/reminders.log 2>&1

if event_type == "call.no_answer":
    send_sms(patient_phone, f"Missed your call! Confirm your appt here: {confirm_link}")

# In your system prompt:
"Available slots tomorrow: 9am, 11am, 3pm. Offer these if they want to reschedule."

curl -X POST https://api.voipbin.net/v1.0/auth/signup \
  -H "Content-Type: application/json" \
  -d '{"username": "you", "password": "yourpass"}'