Voice AI Pricing: Hidden Costs and How to Calculate True ROI

Bolti, a voice AI platform for building production-ready conversational phone agents, offers a transparent starting rate of ‹7/minute pay-as-you-go, alongside a 50-minute free trial to help you test your setup. When evaluating voice AI pricing, looking only at the platform's sticker price is a common mistake. A production-ready voice call relies on multiple underlying technologies, each contributing to the total cost.

To build an accurate budget, you must understand how these components interact and how different providers impact your final bill.

What is the true cost structure of voice AI pricing?

The true cost of a voice AI call is the sum of four distinct technology layers: Speech-to-Text (STT), the Large Language Model (LLM), Text-to-Speech (TTS), and telephony routing.

Caller's audio │ ▼[STT] Speech-to-Text (‹/min) │ ▼[LLM] Large Language Model (‹/token) │ ▼[TTS] Text-to-Speech (‹/character) │ ▼[Telephony] PSTN/SIP Trunk (‹/min)

When you make a call on Bolti, you do not have to negotiate contracts with four separate vendors. Bolti pools these services, but your choices within each category directly influence your overall performance and expenses.

1. Speech-to-Text (STT) Pricing

STT engines transcribe the caller's spoken words into text. This is billed per minute of audio processed.

• Global Defaults: Providers like Deepgram or AssemblyAI offer fast, accurate transcription for English and major European languages.
• Regional Specialists: For Indian-language calls (such as Hindi, Marathi, Tamil, or Telugu), engines like Fennec or SarvamAI deliver better accuracy for regional accents, preventing costly misunderstandings that lengthen calls.

2. Large Language Model (LLM) Pricing

The "brain" of your agent reads the transcription and decides what to say next. LLMs are billed based on tokens (units of text) consumed and generated.

• High-Reasoning Models: OpenAI's GPT-4o family handles complex, multi-turn logic but costs more per token.
• Low-Latency Models: Google Gemini 2 Flash or Llama models hosted on Groq's hardware offer ultra-fast responses and lower token costs, making them ideal for high-volume customer service.

3. Text-to-Speech (TTS) Pricing

TTS converts the LLM's text response back into spoken audio. This layer is billed per character or per thousand characters.

• Ultra-Realistic Voices: ElevenLabs (using Eleven Turbo v2.5) provides incredibly human-like voices but sits at a premium tier.
• Low-Latency, Multilingual Voices: Cartesia (using the Sonic-3 model) balances low latency with competitive pricing.
• Indian-Language Voices: SarvamAI (featuring voices like Anushka) provides natural-sounding Indian languages at localized rates.

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 per-minute rate. With Bolti, you can bring your own carrier (BYOC) using existing SIP credentials from Twilio, Plivo, or Exotel, or purchase phone numbers directly through the platform.

How do different voice AI providers compare on cost?

Choosing the right combination of providers requires balancing latency, quality, and cost. If you optimize solely for cost, you may end up with high latency (sluggish responses over 800ms) that causes callers to hang up. If you optimize solely for quality, your unit economics might not scale.

Here is how common provider configurations stack up on Bolti:

• The Cost-Optimized Setup: Deepgram (STT) + Gemini 2 Flash (LLM) + Cartesia (TTS). This combination minimizes per-minute costs while maintaining sub-second latency, making it perfect for high-volume outbound campaigns.
• The High-Expressiveness Setup: Deepgram (STT) + GPT-4o (LLM) + ElevenLabs (TTS). This configuration is best for premium inbound sales where natural cadence and deep reasoning are vital, though it carries a higher per-minute cost.
• The India-First Setup: Fennec or Sarvam (STT) + Llama-3 on Groq (LLM) + SarvamAI (TTS). This setup is specifically tuned for Indian languages and accents, ensuring high comprehension rates without paying premium global rates.

To understand how these configurations align with your business goals, explore our guide on Bolti use cases.

What are the hidden costs of scaling voice AI campaigns?

Beyond raw infrastructure fees, scaling a voice AI operation introduces operational costs that can catch teams off guard if they are not planned for in advance.

• Failed and Retried Calls: If you run bulk campaigns, you will pay for calls that hit voicemail or get dropped. Bolti's batch-calling scheduler automatically manages retry budgets, but those minutes still count toward your telephony usage.
• Integration and Webhook Overhead: Triggering downstream actions (like updating your CRM via webhooks when a conversation.completed event fires) requires server resources. Bolti's durable webhook outbox ensures at-least-once delivery, saving your developers from building expensive queueing infrastructure.
• Workspace and Sub-account Management: If you are an agency or enterprise managing multiple clients, setting up separate billing pipelines can be complex. Look for platforms that offer sub-accounts with white-label capabilities to simplify billing administration.

For a detailed breakdown of these hidden operational expenses, read our analysis on the hidden costs of voice AI platforms.

How to calculate your voice AI ROI

To determine if voice AI is cost-effective for your business, compare the fully loaded cost of a human agent against your voice AI per-minute rate.

1. Calculate human agent cost per minute: Divide an agent's total monthly cost (salary, benefits, overhead, and software licenses) by the actual minutes they spend talking to customers.
2. Calculate voice AI cost per minute: Combine your platform fee (such as Bolti's ‹7/minute starting rate) with your average telephony and provider costs.
3. Factor in utilization: Human agents are rarely on calls 100% of their shift due to breaks, training, and wrap-up work. Voice AI agents only cost money when they are actively speaking on the phone, meaning you pay ‹0 during idle hours.

For exact platform tiers and volume discounts, check the official Bolti pricing page.

Set up your first voice agent with Bolti

Ready to see how voice AI fits into your budget? You can build, configure, and test your first multilingual voice agent in under 10 minutes on Bolti. Sign up today to get 50 free minutes of call time and test different STT, LLM, and TTS combinations live.

Frequently Asked Questions

What is the starting price for Bolti?

Bolti starts at ‹7 per minute on a pay-as-you-go basis. New accounts also receive a free trial with 50 minutes of call time to test the platform.

Can I use my own telephony provider with Bolti?

Yes. Bolti supports Bring Your Own Carrier (BYOC), allowing you to connect your existing SIP trunks from providers like Twilio, Plivo, or Exotel.

How do different LLMs affect the cost of a voice call?

LLMs charge based on token usage. Larger, high-reasoning models like GPT-4o cost more per token, while smaller, speed-optimized models like Gemini 2 Flash or Llama on Groq cost significantly less, reducing your overall per-minute rate.

Are there extra charges for multilingual or regional voices?

Pricing depends on the TTS provider you select. Global providers like ElevenLabs carry premium rates, while regional specialists like SarvamAI offer cost-effective rates for Indian languages like Hindi.