How voice AI works
Every conversation flows through a three-step pipeline that happens in real-time:Listen
Speech-to-Text (ASR) converts the caller’s voice into text that your AI can understand.Bolna supports Deepgram, Azure, ElevenLabs, and more.
Think
Large Language Model (LLM) processes the text, understands context, and generates an intelligent response.Connect OpenAI, Anthropic, Azure OpenAI, or your own LLM.
Speak
Text-to-Speech (TTS) converts the response into natural-sounding speech played back to the caller.Choose voices from ElevenLabs, Cartesia, Azure, and more.
Bolna orchestrates this entire pipeline in under 600ms, enabling natural, real-time conversations with minimal latency.
Agents can also run on a single speech-to-speech model that hears and speaks directly, without the separate transcribe and synthesize steps. See speech-to-speech agents.
Key terms
New to voice AI? The Glossary explains every term used across these docs in plain English, including LLM, transcriber (ASR), synthesizer (TTS), telephony provider, prompt, latency and knowledge base (RAG).What can Bolna agents do?
Handle phone calls
Inbound calls
Answer customer calls 24/7 with AI-powered responses
Outbound calls
Proactively reach customers for sales, reminders, and follow-ups
Batch calling
Launch campaigns with thousands of concurrent calls
Call transfer
Route to human agents when AI assistance isn’t enough
Execute actions during calls
Agents can perform real-time actions by calling external APIs and tools:Built-in Function Tools
Built-in Function Tools
Extract insights after calls
Every conversation generates valuable data:Transcripts
Full conversation text with speaker labels
Recordings
Audio recordings for review and training
Summaries
AI-generated call summaries
- Customer intent and sentiment
- Key data points (name, email, order ID)
- Custom fields you define
Agent configuration
Every Bolna agent is customized through 7 configuration tabs:- Core Settings
- Call Settings
Agent tab
Prompts & PersonalityDefine your agent’s welcome message, instructions, and conversation behavior.
Intelligence tab
Intelligence & KnowledgeChoose your language model and connect knowledge bases for context-aware responses.
Languages tab
Voice & TranscriptionSelect voice provider, language, and transcription settings.
Engine tab
Latency, Behavior & HangupFine-tune response timing, interruption handling, user detection, the final call message, and call timeouts.
The former Inbound tab has been merged into Calling. Toggle on Inbound Calling there to pick an inbound number, match callers to a database and set spam limits — see Inbound Calling settings.
Next steps
What happens during a call
Follow one call from dial to webhook, with every status it passes through
Agent types
Choose between the agent types Bolna supports
Glossary
Look up any term used in the docs
Build your first agent
Generate a call-ready agent from a short description

