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Building AI Voice Agents

Everything you need to create, configure, and deploy AI agents that make real phone calls — in 22 Indian languages.

Introduction

An AI Voice Agent on Vaaad AI is a configurable voice assistant that can make outbound calls or answer inbound calls on your behalf. Each agent has its own personality, script, language, voice, and optional knowledge base — and can handle thousands of conversations simultaneously.

This guide walks you through creating your first agent, crafting the perfect system prompt, designing a call flow, linking a Knowledge Base, and going live.

Video walkthrough — Building your first agent

Creating Your First Agent

Head to the Agents page in your dashboard and click + New Agent. You'll see a slide-out panel with every configuration option.

  1. Agent Name — internal label (e.g., “APEX Sales Bot”). Customers never see this.
  2. Description — a quick note for your team about what this agent does.
  3. Active toggle — keep off until you've tested. Only active agents can receive calls.

Writing the Perfect System Prompt

The System Prompt is the most important field. It's the instruction manual for your agent — telling it who it is, what it does, and how to behave. A well-written prompt is the difference between an agent that feels human and one that feels robotic.

Structure of a great prompt

We recommend breaking your prompt into clear sections:

# IDENTITY
You are a friendly, professional real estate assistant
named APEX, calling on behalf of Aditya Realty.

# OBJECTIVE
Qualify leads by asking 4 questions:
1. Are they buying or renting?
2. What's their budget range?
3. Preferred location?
4. Timeline to move?

# STYLE
- Warm, conversational, never pushy
- Use "aapka" (formal Hindi) not "tumhara"
- Keep each response under 20 seconds
- Acknowledge what the user says before responding

# RULES
- Never discuss price directly on the call
- If asked for specifics, say: "Our team will follow up
  with details via WhatsApp"
- If the user asks to stop, end the call politely
💡
Pro tip: Start with a short prompt and iterate based on real call recordings. Don't try to cover every edge case upfront — listen to how your agent actually performs and refine from there.

What makes a prompt bad

  • Too long — prompts over 4000 characters slow down response time
  • Contradictions — “Be formal” + “Be casual and friendly”
  • No identity — agent doesn't know its own name or company
  • Missing objective — agent rambles instead of driving the conversation

Initial Greeting

The Initial Greeting is the first thing your agent says when the call connects. Keep it under 8 seconds and include three elements:

  1. Who is calling (name + company)
  2. Why they're calling (one-line context)
  3. A soft question or pause for the user to respond
Namaste, main APEX hoon, Aditya Realty se. Hum abhi Jaipur ke kuch properties ke liye calls kar rahe hain. Aapko ek minute ho sakta hai?

Language & Voice

Vaaad AI supports 22 Indian languages. For each agent, pick:

  • Language — Hindi, Hinglish, English, Tamil, Punjabi, Marathi, Bengali, Telugu, and 14 more
  • Voice — each language has multiple voice options (male/female, warm/professional)

Hinglish works best for most Indian business calls — it sounds natural and switches between Hindi and English the way real people do.

Designing a Call Flow

Most effective agents follow a simple 5-step flow. Build your prompt around this structure:

  1. Open — greet + state reason for call
  2. Permission — “Is this a good time?” (respects the user)
  3. Qualify — 3-5 questions to understand the need
  4. Value — share the relevant info or offer
  5. Close — confirm next step (WhatsApp follow-up, meeting, callback)

Linking a Knowledge Base

If your agent needs to answer specific factual questions — product details, pricing, policies, addresses — attach a Knowledge Base document. The agent will only pull answers from your documents, never make things up.

How to link:

  1. Go to the Knowledge Base page and upload your docs (PDF, DOCX, TXT)
  2. Open your agent in the Agents page
  3. Scroll to Linked Documents and select the docs to attach
  4. Save. The agent will now use RAG to retrieve relevant info during calls.
🔗
KB docs are shared across agents. Upload once, attach to multiple agents. Any doc you update is reflected everywhere it's linked.

Human Handoff

If the user asks to speak to a human (“transfer me”, “insaan se baat karao”), your agent can warm-transfer the call to a real person. Configure this in the agent settings:

  • Transfer Number — the human's phone number (with country code)
  • Trigger Phrase — optional custom phrase (Vaaad auto-detects 30+ phrases in English, Hindi, and Hinglish)

When triggered, the agent says “I'm connecting you to our team” and dials the human in 2-3 seconds.

Testing Your Agent

Before running a campaign, always test with your own number:

  1. Make your agent active
  2. Click New Call from any page
  3. Enter your own phone number and select the agent
  4. Answer the call and run through every branch of your script
  5. Review the recording and transcript in the Calls page

Iterate until it feels natural. Most good agents take 3-5 iterations on the system prompt before they're launch-ready.

Going Live

Once tested, your agent can be used for:

  • One-off calls — via the New Call button anywhere in the dashboard
  • Campaigns — upload a contact list and call thousands at once. See Call Campaigns
  • Inbound — assign a phone number to the agent for incoming calls

Next: Automate outbound calls with Campaigns →