How to build an AI voice agent for your business — a practical guide
How to build an AI voice agent for your business — a practical guide
AI & Automation • technical guide
Table of Contents
What an AI voice agent actually is and is not
An AI voice agent is an autonomous conversational AI system capable of handling two-way spoken phone calls in natural language. It is **not** an IVR push-button phone tree ("Press 1 for Sales"). Modern AI voice agents listen to human speech, convert audio to text (STT), process context through an LLM (OpenAI GPT-4o), and generate sub-800ms spoken responses via Text-to-Speech (TTS).Need a custom quantitative solution?
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- **Telephony Provider (Twilio/Telnyx)**: Provisions phone numbers and routes inbound SIP/PSTN audio streams. - **Orchestration Layer (VAPI/Retell)**: Manages low-latency speech pipelines, WebSockets, and interruption detection. - **Intelligence (OpenAI GPT-4o-mini)**: Executes prompt instructions, retrieves knowledge base context, and triggers tool functions. - **Voice Generation (ElevenLabs/Deepgram)**: Converts LLM text response into human voice audio.What you need before you build
1. **System Prompt & Guardrails**: Clear conversational flow, role persona, and boundary handling. 2. **Knowledge Base (RAG)**: FAQs, pricing, service policies, and operating hours formatted for fast lookup. 3. **Calendar / CRM Integrations**: Webhook endpoints connecting to Cal.com, GoHighLevel, or HubSpot for live appointment booking.What it costs to run
Operating costs average $0.09 - $0.18 per minute of live phone conversation, combining telephony, STT, LLM tokens, and TTS voice generation.About the PSI Square Team
We are a team of quantitative developers, AI system architects, and full-stack software engineers specializing in execution latency optimization, autonomous systems orchestration, and custom broker integrations.
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