Sigma Voice AI: The 24/7 AI Receptionist That Never Misses a Call

37% of business calls go unanswered. Every missed call is a missed customer — someone who needed your service right now and called your competitor instead. For small businesses without a full-time receptionist, the phone is the single biggest revenue leak. Sigma Voice AI was built to fix that.

Sigma Voice AI is a fully autonomous AI phone receptionist that answers every call, handles customer inquiries, checks appointment availability in real time, books appointments directly into your calendar, sends SMS confirmations, and transfers to a human when needed — all without a single missed ring.

The Problem: Your Phone Is Costing You Money

Here's a scenario every small business owner knows: A potential customer calls during lunch. Nobody picks up. They call your competitor. That customer is gone forever. Multiply that by 5-10 missed calls a week and the math gets painful fast.

The average value of a new customer call varies by industry, but the numbers are real:

• Medical/MedSpa: $500-$2,000+ per new patient (treatments, follow-ups, referrals)
• HVAC/Plumbing: $300-$1,500 per service call (emergency calls are the highest value)
• Legal: $1,000-$10,000+ per case (one missed intake call can cost thousands)
• Dental: $500-$3,000 per new patient (cleanings lead to crowns, implants, referrals)
• Auto Repair: $200-$800 per repair job (and repeat customers for years)

A full-time receptionist costs $35,000-$50,000/year. An answering service costs $200-$1,000/month and still can't book appointments or answer service-specific questions. Sigma Voice AI starts at $299/month and does both — 24 hours a day, 7 days a week, with zero sick days.

Case Study: Lodi MedSpa — Live Demo

Our first live deployment is Sophia, the AI receptionist for Lodi MedSpa in Lodi, California. Sophia handles every incoming call to (209) 921-5634 and demonstrates exactly what Sigma Voice AI can do for any business.

Here's what happens when you call:

• 1.Sophia introduces herself and discloses she's an AI assistant (required by California AB 2905). No awkward scripts — she sounds natural and conversational.
• 2.She answers your questions about any of the 11 services offered: Botox, dermal fillers, microneedling, weight loss injections, IV hydration, hormone therapy, PDO threads, PRF, Sculptra, Radiesse, and peptide therapy. She knows pricing, duration, downtime, and expected results.
• 3.She checks live availability by querying the Cal.com calendar in real time. She tells you exactly which time slots are open on your preferred date.
• 4.She books the appointment directly into the calendar, collects your name and phone number, and confirms the details back to you.
• 5.She sends an SMS confirmation with the appointment date, time, service, and location so you have everything in writing.
• 6.She transfers to a human when the caller requests it or when the question requires human judgment (medical advice, complex billing, complaints).

Every call is logged to a database with caller information, call duration, and outcomes. After appointments, the system can automatically send review request SMS messages to build the business's Google review count.

How It Works Under the Hood

Sigma Voice AI isn't a simple IVR menu or a chatbot reading a script. It's a fully autonomous AI agent powered by a large language model with real-time tool access. Here's the technical architecture:

• Voice Platform: SignalWire AI handles the telephony — answering calls, speech-to-text, text-to-speech with ElevenLabs for natural-sounding conversation
• AI Brain: A large language model processes the conversation and decides which tools to call — service lookup, availability check, booking, or transfer
• SWAIG Functions: Custom webhook functions that give the AI real-time access to your business data: service details, pricing, availability, and booking capabilities
• Calendar Integration: Cal.com API for real-time availability checks and instant appointment booking — no double-bookings, no manual entry
• SMS Confirmations: Automatic text messages via SignalWire after every booking with date, time, service, and location
• Call Logging: Every call is stored in Supabase with caller data, timestamps, and outcomes for analytics and follow-up

The entire system is built on Sigma Agents' infrastructure and deployed on Vercel, meaning it scales automatically. Whether your business gets 5 calls a day or 500, the AI handles them all with zero additional cost per call.

What Sigma Voice AI Can Do

How Other Industries Can Use Sigma Voice AI

Lodi MedSpa is just the first deployment. Sigma Voice AI is designed to work for any service-based business that takes phone calls. Here's how it adapts to different industries:

HVAC & Plumbing

Emergency calls at 2 AM are the highest-value calls in home services — and the most frequently missed. Sigma Voice AI answers every emergency call instantly, triages the issue (is it a burst pipe or a dripping faucet?), checks technician availability, and schedules the appointment. For after-hours calls, it can take caller information and dispatch a callback first thing in the morning. No more voicemail black holes.

Dental Practices

The front desk is the bottleneck in every dental office. When the receptionist is checking in patients, the phone goes to voicemail. Sigma Voice AI handles overflow calls during busy hours and covers after-hours entirely. It knows your services (cleanings, crowns, implants, emergency extractions), can answer insurance questions from your FAQ, and books directly into your scheduling system.

Law Firms

For law firms, especially personal injury and family law, the initial call is everything. If a potential client calls and nobody picks up, they call the next firm on the list. Sigma Voice AI can handle intake screening — asking about the type of case, when the incident occurred, and basic contact information — then route qualified leads to the right attorney or schedule a consultation.

Auto Repair & Detailing

Mechanics are under cars, not at the phone. Sigma Voice AI answers calls while your team works, provides estimates for common services (oil change, brake pads, tire rotation), checks appointment availability, and books the job. Customers get immediate answers instead of leaving a message and hoping for a callback.

Salons & Spas

Beauty businesses run on appointments. When stylists are with clients, the phone rings and nobody answers. Sigma Voice AI knows your menu of services, pricing, and availability. It can recommend services based on what the caller describes (“I want something for my acne scars” → microneedling), book the right length appointment, and send confirmations.

Real Estate

Agents can't answer the phone during showings, closings, or client meetings. Sigma Voice AI qualifies incoming buyer/seller leads, asks about their timeline, budget, and preferred area, then schedules a callback or consultation with the right agent. No lead sits in a voicemail for hours.

Pricing

Sigma Voice AI is part of the Sigma Workforce AI product line. Pricing is straightforward:

Compare that to a full-time receptionist ($35,000-$50,000/year), an answering service ($200-$1,000/month with no booking capability), or the cost of missed calls (potentially thousands per month in lost revenue). Sigma Voice AI pays for itself with one or two captured calls that would have otherwise gone to voicemail.

What Makes Sigma Voice AI Different

There are other AI phone solutions on the market. Here's what sets Sigma Voice AI apart:

• Real booking capability — Most AI phone systems just take messages. Sigma Voice AI actually books appointments into your live calendar with real-time availability.
• Deep business knowledge — The AI knows your services, pricing, duration, downtime, and can answer detailed questions. It's not reading from a generic script.
• Natural conversation — ElevenLabs voice synthesis makes the AI sound like a real person, not a robot. Callers often don't realize they're talking to AI until the disclosure.
• Compliance built in — California AB 2905 and Penal Code Section 632 require AI disclosure and recording consent. Sigma Voice AI handles this automatically on every call.
• Part of a larger platform — Sigma Voice AI is one module in the Sigma Workforce AI suite. Chat, email, scheduling, and review management agents are coming, all integrated into one platform.

Getting Started

Setup is straightforward. We configure your AI receptionist with your business information, services, pricing, and hours. We connect it to your calendar system, assign a local phone number, and you're live. Most businesses are up and running within a week.

The onboarding process:

• 1.Discovery call — We learn your business, services, pricing, hours, and how you want calls handled
• 2.Knowledge base build — We create your AI's knowledge base with service details, FAQs, and business rules
• 3.Calendar integration — We connect to your existing scheduling system (Cal.com, Calendly, or custom)
• 4.Testing — We test every scenario: service inquiries, booking flow, edge cases, transfers
• 5.Go live — Your AI receptionist starts answering calls. We monitor the first week closely and fine-tune based on real conversations.

Every day you wait, calls go to voicemail and customers go to competitors. Sigma Voice AI makes sure that never happens again.