LLM

OpenAI

Power your Bolna voice agents with GPT-4o, GPT-4o-mini, or GPT-3.5 using your own API key. Fast, accurate language understanding for every phone call.

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Official Documentation

At a glance

How OpenAI fits in the stack

Best for

Reasoning, policy handling, tool use, and response generation.

Use this layer when

You want to tune quality, cost, latency, or function-calling behavior.

Connects to

Transcribed caller input upstream and voice or actions downstream.

Voice Stack

The LLM is the reasoning layer

This provider decides how the agent interprets intent, selects next actions, calls tools, and formulates responses. It is the decision engine inside the voice stack.

TelephonyPhone Network

→

STTListener

→

LLMReasoning

→

TTSVoice

→

ToolsActions

This page focuses on where OpenAI fits in a production voice stack. For full setup steps, credentials, and API details, use the documentation link above.

Overview

OpenAI provides state of the art large language models that power intelligent voice agents. With Bolna's OpenAI integration, you can leverage GPT-4o, GPT-4o-mini, and GPT-3.5 Turbo to create conversational AI agents that understand context, generate natural responses, and handle complex queries.

OpenAI models are the brain of your voice agent, they process what the caller says, understand their intent, and generate appropriate responses in realtime during phone conversations.

Features & Use Cases

Top Performance (GPT-4o)
The smartest model available. It easily understands complex requests and speaks very naturally. Perfect for handling tricky customer support issues or detailed technical questions.

Fast & Affordable (GPT-4o-mini)
A cheaper and faster version of the top model that still does a great job. It is ideal for busy call centers where you need quick answers without spending too much.

Quick & Basic (GPT-3.5 Turbo)
Extremely fast and highly affordable. Great for handling simple tasks like booking appointments or answering basic questions instantly.

Can Take Actions (Function Calling)
The AI doesn't just talk - it can actively do things for you during a call, like securely booking an appointment, updating a customer file, or checking on an order status.

Great Memory (Large Context Window)
Can remember very long conversations, making sure the AI agent never forgets what the caller said earlier in the call.

Other providers in this layer

LLM

Anthropic

Connect Anthropic Claude to your Bolna voice agents for smart, natural conversations. Handles complex multi-turn dialogue with 200K token context windows.

LLM

Azure OpenAI

Run OpenAI models on Azure with Bolna voice agents. Get enterprise compliance, SLAs, and data residency while powering intelligent phone conversations.

LLM

DeepSeek

Use DeepSeek with Bolna voice agents for strong reasoning at a fraction of the cost. Great for high-volume voice automation where every token counts.

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Keep exploring the voice stack

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Large Language Models

The LLM is the brain of your voice agent. It understands what callers say and decides how to respond. Bolna lets you swap between models like GPT-4o, Claude, and DeepSeek without changing your agent configuration, so you can optimize for speed, cost, or reasoning depth.

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Telephony

Telephony providers connect your voice agents to the phone network so they can make and receive real calls. Bolna supports managed integrations with major carriers as well as bring-your-own-carrier via SIP trunking, giving you full control over call routing, number provisioning, and cost.

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Speech-to-Text

Speech-to-text converts what callers say into text that your LLM can process. Transcription accuracy and latency directly affect how natural a conversation feels. Bolna supports streaming STT providers optimized for telephony audio, including specialized models for Indian languages.

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Text-to-Speech

Text-to-speech turns your agent responses into spoken audio. Voice quality shapes how callers perceive your brand. Flat, robotic speech kills trust while natural, expressive voices build it. Bolna integrates with the fastest TTS providers so responses sound human and arrive without awkward pauses.

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Tools & Workflows

Tools let your voice agents take action during a call, not just talk. Book a calendar slot, look up an order in Shopify, push a lead into your CRM, or trigger a multi-step automation in Zapier. These integrations turn voice agents from answering machines into workflow engines.

See where OpenAI fits in your production workflow

Use the demo to walk through provider selection, stack tradeoffs, and the exact workflow you want Bolna to automate.

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