What is a voice agent?
A voice agent is software that can carry on a full spoken conversation with a human in real time. Unlike a traditional IVR ("press 1 for sales") or a text chatbot, a voice agent understands open-ended speech, reasons with a large language model, and responds with human-sounding synthesized voice — handling interruptions, accents, and topic switches the way a person would.
The breakthrough that made this possible is end-to-end streaming. Every layer — speech recognition, the LLM, and text-to-speech — now streams tokens, so the agent can start replying before the user has even finished speaking.
Voice agent vs. chatbot vs. IVR
- Open-ended speech — Only voice agents handle it. IVRs use rigid menus; chatbots are text-only.
- Interruption (barge-in) — Voice agents support it; IVRs and chatbots don't.
- Multi-turn reasoning — Voice agents excel; chatbots are limited; IVRs can't.
- Latency target — Voice agents aim for under 800ms; chatbots tolerate 1–3s.
- Indic languages — Growing fast for voice agents, broad for chatbots, sparse on IVRs.
The voice agent stack
- Transport — Twilio, Plivo, or LiveKit for telephony / WebRTC.
- Speech-to-text (STT) — Deepgram, Whisper, Sarvam, AI4Bharat.
- LLM — Gemini, GPT, Claude, or open Llama / Mistral on Lovable Cloud.
- Text-to-speech (TTS) — ElevenLabs, Cartesia, Sarvam for Indic voices.
- Orchestrator — Pipecat, LiveKit Agents, or Vapi to wire the loop together with VAD and barge-in.
Where voice agents shine
- Healthcare intake — Pre-visit triage in Hindi, Tamil, or Bengali for tier-2/3 clinics.
- Field sales & collections — Outbound calls to small merchants who don't read English.
- Education — Spoken-English tutors that practice with students 1:1.
- Customer support — Replacing 60% of L1 tickets without losing CSAT.
- Logistics — Drivers who can't type but need to update job status by voice.
- Government services — Citizen helplines at a fraction of human-agent cost.
Building one in India
Indian voice AI has unique constraints — code-switching between English and Indic languages mid-sentence, noisy 2G/3G call quality, and accents the global models still struggle with. The good news: local models from Sarvam and AI4Bharat now match or beat global STT/TTS for Indic languages, and they're cheap enough to run at scale.
AIGI grants give Indian builders free compute and credits across the full voice stack so the first 100k minutes don't come out of your runway.
Frequently asked
What is a voice agent?
A voice agent is an AI system that listens to spoken input, understands intent using a language model, and responds with synthesized speech in real time — typically with sub-second latency so the conversation feels natural.
How is a voice agent different from a chatbot?
Chatbots exchange text. Voice agents handle the full speech loop: speech-to-text, reasoning with an LLM, and text-to-speech — plus interruption handling, turn-taking, and barge-in detection that text never needs.
What does a voice agent stack look like?
A typical stack: a telephony or WebRTC layer (Twilio, LiveKit), a streaming STT model (Deepgram, Whisper), an LLM (Gemini, GPT, Llama), and a TTS model (ElevenLabs, Cartesia, Sarvam for Indic). An orchestrator like Pipecat or Vapi glues them together.
What latency is acceptable for a voice agent?
Sub-800ms end-to-end response time feels conversational. Above 1.5s users start to interrupt or hang up. Streaming every layer — STT, LLM, TTS — is what gets you there.
Can I build a voice agent in Indian languages?
Yes. Sarvam, AI4Bharat, and Reverie offer production STT/TTS for Hindi, Tamil, Telugu, Bengali, Marathi, and more. AIGI funds teams building Indic voice agents with free credits across these providers.