Bolti AI - Automated Call Agent Platform Logo

Voice Price: How Voice AI Call Pricing Works in 2026

Dhiraj··Updated 31 August 2026

Founder of Bolti, writing about voice AI for Indian businesses.

When you build a conversational phone agent, calculating your operational costs can feel like solving a multi-variable calculus problem. Bolti, a voice AI platform for building production-ready conversational phone agents, simplifies this with a transparent, predictable pricing model. For just ₹6/min on our pay-as-you-go plan (including a free trial with 50 minutes), you can deploy high-performance voice agents without hidden fees.

But if you are comparing platforms or planning to scale to lakhs of calls, you need to understand how the underlying "voice price" is calculated. The cost of a voice AI call is not a single flat fee; it is the sum of four distinct pipeline stages running in real-time. This guide will break down those components, show you how to calculate your true cost per minute, and explain how to optimize your setup for maximum efficiency.

What factors determine the voice price of an AI call?

The total voice price of an AI phone call is determined by four core pipeline stages: Speech-to-Text (STT), the Large Language Model (LLM), Text-to-Speech (TTS), and Telephony. Every second your caller is on the line, these four services process data concurrently to keep the conversation flowing naturally with sub-second latency.

Caller's audio ──▶ [STT] (Per second/minute) 
                  └──▶ [LLM] (Per input/output token) 
                        └──▶ [TTS] (Per character/character count)
                              └──▶ [Telephony] (Per minute over PSTN/SIP)

Unlike traditional platforms that bundle these into an expensive, opaque markup, Bolti gives you direct control over your pipeline. You can mix and match providers for each stage to balance quality, latency, and cost.

Here is how each component contributes to your overall voice price:

1. Speech-to-Text (STT) Pricing

STT providers transcribe your caller’s spoken words into text so the LLM can read them. This is typically billed per second or per minute of audio processed.

  • Global Defaults: Providers like Deepgram or AssemblyAI offer highly accurate English transcription at low rates.
  • Regional Specialists: For Indian-language calls, providers like Fennec or Sarvam-backed STT offer superior accuracy for regional accents and mixed-language (Hinglish) conversations.

2. Large Language Model (LLM) Pricing

The LLM acts as the brain of your agent, deciding what to say next and when to trigger external tools. LLMs are billed based on "tokens" (chunks of words) processed:

  • Input Tokens: The system prompt, the conversation history, and the latest STT transcript fed into the model.
  • Output Tokens: The text response generated by the model.

Using lightweight models like Google Gemini 2 Flash or Llama-family models on Groq drastically reduces your LLM costs while maintaining sub-second response times. Highly complex reasoning tasks might require OpenAI's GPT-4o family, which increases the per-token cost but provides deeper cognitive capabilities.

3. Text-to-Speech (TTS) Pricing

TTS converts the LLM's text response back into lifelike audio. This is almost always billed per character (including spaces and punctuation). TTS is often the largest variable cost in a voice pipeline.

  • Premium Voices: Providers like ElevenLabs (using Eleven Turbo v2.5) offer ultra-realistic, emotionally expressive voices but at a higher cost per character.
  • High-Speed, Low-Cost Voices: Providers like Cartesia (using the Sonic-3 model), SmallestAI, and SarvamAI offer an exceptional balance of low latency, natural pronunciation, and budget-friendly pricing.

4. Telephony Pricing

Telephony is the physical pipe that carries the call over the public switched telephone network (PSTN) or SIP trunks. This is billed as a flat rate per minute. With Bolti's Bring Your Own Carrier (BYOC) architecture, you can connect your existing SIP trunks (such as Twilio, Plivo, or Exotel) to keep your carrier rates, or use Bolti-provided phone numbers directly.

How do you calculate your cost per minute?

To calculate your true voice price per minute, you must estimate the volume of data flowing through each stage of the pipeline during a standard 60-second conversation.

Let's look at a typical customer support scenario in India using a balanced, high-performance stack:

  • STT: Deepgram (for English) or Fennec (for Hindi/Indic languages)
  • LLM: Gemini 2 Flash
  • TTS: Cartesia or SarvamAI
  • Telephony: Indian PSTN routing

Here is how the math breaks down for a 1-minute call:

  1. Telephony: A flat rate of approximately ₹0.50 to ₹1.00 per minute depending on your carrier.
  2. STT processing: 60 seconds of active stream transcription costs roughly ₹0.80.
  3. LLM tokens: A standard back-and-forth conversation uses about 1,500 input tokens (including system prompts and history) and 300 output tokens per minute. On Gemini 2 Flash, this costs less than ₹0.10.
  4. TTS characters: If your agent speaks 150 words (approximately 900 characters) during the minute, TTS costs roughly ₹1.20 using a low-latency provider like Cartesia.

Total Estimated Cost: ~₹2.60 to ₹3.10 per minute of continuous talk time when buying raw APIs directly.

With Bolti's fully managed platform, we handle the complex infrastructure, real-time streaming, interruption handling, and noise cancellation, offering an all-inclusive pay-as-you-go rate of just ₹6 per minute. This saves your engineering team months of building and debugging real-time WebSocket connections. You can review our transparent pricing tiers on the Bolti pricing page.

How to optimize your voice AI agent for lower costs

You do not have to sacrifice quality to lower your voice price. Because Bolti allows you to customize your provider stack per agent, you can optimize individual components based on your specific Bolti use cases.

Use these strategies to keep your operational costs low:

  • Write Concise System Prompts: LLM billing is cumulative. Keep your agent's system prompts clear and direct. Avoid bloated instructions to minimize input token costs on every turn.
  • Match the Model to the Task: Do not use expensive reasoning models for simple lead qualification or appointment routing. A fast, cost-effective model like Groq Llama or Gemini 2 Flash is more than capable of handling 90% of transactional customer service calls.
  • Truncate Conversation History: Instead of sending a 30-minute chat transcript back to the LLM on every turn, configure your agent to summarize older turns or only retain the last 5–10 exchanges.
  • Select the Right TTS Provider: For high-volume outbound campaigns like payment reminders, use fast and lightweight TTS engines like SmallestAI or Cartesia. Save ultra-realistic, premium engines like ElevenLabs for high-value inbound sales lines.

Set up your first voice agent in 2026

Ready to see how cost-effective voice AI can be for your business? With Bolti, you can design, test, and deploy a multilingual voice agent in minutes without writing a single line of code.

Sign up today to get 50 free minutes of call time to test our low-latency platform. Experience sub-second response times, native interruption handling, and crystal-clear regional language voices firsthand.

Create your free Bolti account and launch your first voice agent today.

Frequently Asked Questions

What is included in Bolti's ₹6/minute voice price?

Bolti's standard pay-as-you-go rate of ₹6/minute includes the entire real-time voice pipeline: Speech-to-Text (STT), Large Language Model (LLM) processing, Text-to-Speech (TTS), and telephony minutes. It also covers our advanced runtime features like real-time interruption handling, telephony-grade noise cancellation, and sub-second turn-taking.

Can I bring my own SIP trunk or carrier to Bolti?

Yes. Bolti supports Bring Your Own Carrier (BYOC). You can connect your existing SIP trunks from providers like Twilio, Plivo, or Exotel. This allows you to leverage your pre-negotiated carrier rates while using Bolti's voice AI orchestration.

How does the free trial work?

When you sign up for a Bolti account, you automatically receive 50 free minutes of call time. No credit card is required to start. You can use these minutes to test different voices, LLM prompts, and tool integrations in our browser-based preview tool or on real phone calls.

Which languages are supported on Bolti?

Bolti supports over 80 global languages, including English, Hindi, Marathi, Tamil, Telugu, Bengali, Gujarati, and Kannada. We partner with specialized regional providers like SarvamAI and Fennec to ensure high-accuracy transcription and natural accents for Indian languages.