Voice AI Cost Per Call: What You Actually Pay Per Minute (2026)
Bolti is a voice AI platform for production phone agents — and at ₹7/min pay-as-you-go with a free 50-minute trial, it's one of the few platforms where you can calculate your exact bill before committing. This post gives you the full per-call cost model: every layer, every provider fee, and the math you need to budget accurately.
How much does voice AI cost per minute?
Most voice AI platforms charge between ₹5 and ₹25 per minute all-in, but the range is wide because the cost has four separate layers. You're not paying one vendor — you're paying four simultaneously. Understanding each layer is the only way to avoid bill shock.
Here's the standard stack:
| Layer | What it does | Typical cost range |
|---|---|---|
| STT (Speech-to-Text) | Transcribes the caller's audio in real time | ₹0.50–₹2/min |
| LLM (Large Language Model) | Decides what the agent says next | ₹0.50–₹4/min (token-based) |
| TTS (Text-to-Speech) | Synthesizes the agent's voice | ₹0.30–₹2/min (character-based) |
| Telephony | Carries the call over PSTN/SIP | ₹0.50–₹3/min |
Add those up and you're looking at ₹1.80–₹11/min at cost — before any platform markup. Platforms that charge a flat per-minute rate are absorbing that complexity. Platforms that charge you per-component require you to do the math yourself.
Does voice AI cost money? Is it ever free?
Voice AI is not free at scale. Every call consumes real compute: a real STT model transcribes audio in real time, a real LLM generates a reply, a real TTS engine synthesizes audio, and a real phone carrier routes the call. Each of those has a marginal cost.
What you can get for free is testing. Bolti gives every new account 50 free minutes — enough to build a working agent, run it through realistic call scenarios, and validate the experience before you spend anything. After that, you pay ₹7/min with no monthly commitment.
Some platforms advertise free tiers with strict caps (10–25 minutes) or only cover one layer (e.g. free LLM, paid telephony). Read the fine print on what the free tier actually includes.
What hidden fees should you watch for?
Flat per-minute pricing sounds simple, but several platforms add fees on top that don't appear until your invoice arrives.
Common hidden costs:
- Per-call connection fees — a flat charge every time a call connects, regardless of duration
- Phone number rental — monthly fees per number, sometimes per country
- Overage rates — a higher per-minute rate once you exceed a usage tier
- Concurrency limits — extra charges if you run more simultaneous calls than your plan allows
- Premium voice surcharges — certain TTS voices (e.g. ElevenLabs ultra-realistic voices) billed separately
- Inbound vs. outbound rate differences — some platforms charge more for outbound
- BYOC fees — bringing your own SIP trunk (Twilio, Plivo, Exotel) may incur a per-minute passthrough fee
Bolti's model is flat ₹7/min, which covers the full pipeline — STT, LLM, TTS, and telephony. You can see the full pricing breakdown before you sign up.
How does the per-call math actually work?
Let's walk through a concrete example. Suppose you're running an outbound appointment-reminder campaign in Mumbai. Your average call duration is 90 seconds.
Per-call cost at ₹7/min:
- 90 seconds = 1.5 minutes
- 1.5 × ₹7 = ₹10.50 per call
Now scale that:
- 500 calls/day × ₹10.50 = ₹5,250/day
- 10,000 calls/month = ₹1,05,000/month
For comparison, a human agent in a Bangalore BPO costs ₹15,000–₹25,000/month in salary alone — and handles roughly 200–300 calls per day at 3–4 minutes each. The voice AI handles the same volume at a fraction of the cost, with no sick days or shift gaps.
If your calls run longer — say a 5-minute support conversation — the math shifts:
- 5 min × ₹7 = ₹35/call
- Still competitive against human agent cost-per-call of ₹80–₹150 for the same interaction
What affects cost the most?
Three variables drive your actual per-minute bill:
- Call duration — longer calls cost more. Optimise your agent's prompts to resolve intent quickly.
- LLM model choice — GPT-4o costs more per token than a faster, lighter model like Groq-hosted Llama. Bolti lets you swap models per agent, so you can use a cheaper model for simple use cases (payment reminders, appointment confirmations) and a more capable model only where reasoning depth matters.
- TTS voice provider — Cartesia's Sonic-3 model is low-latency and cost-efficient. ElevenLabs ultra-realistic voices cost more per character. Bolti supports both; you choose per agent.
The pipeline Bolti runs on every call:
Caller's voice → STT → LLM → TTS → Caller's ear
Each hop is configurable. See Bolti's provider docs for how provider choices affect your effective per-minute rate.
How does Bolti compare to Vapi, Retell, and other platforms?
The platforms you'll most likely compare include Vapi, Retell AI, Bolna AI, and Ringg AI. Here's a realistic comparison on the dimensions that matter for budgeting:
| Platform | Pricing model | Indian language support | BYOC (own SIP trunk) | Free trial |
|---|---|---|---|---|
| Bolti | ₹7/min flat | Yes (Hindi, Tamil, Telugu, Marathi, Bengali, Gujarati + 80+ languages) | Yes (Twilio, Plivo, Exotel) | 50 free minutes |
| Vapi | Component-based (STT + LLM + TTS + infra billed separately) | Limited | Yes | Limited free tier |
| Retell AI | Per-minute, USD-denominated | Limited | Yes | Limited |
| Bolna AI | Per-minute | Some Indian languages | Partial | Varies |
The key difference with component-based pricing: your bill varies with every call depending on how many tokens the LLM used, how many characters TTS synthesized, and how long the STT ran. Flat per-minute pricing makes forecasting straightforward.
Try Bolti for your first voice AI campaign
You can build a working outbound agent — appointment reminders, payment follow-ups, lead qualification — and run it through 50 real calls before paying anything. At ₹7/min after that, a 1,000-call pilot costs roughly ₹10,500 for 90-second average calls. No contracts, no minimum commitment. Start your free 50-minute trial and have your first agent making calls today.
Frequently Asked Questions
How much does voice AI cost per minute in India?
Voice AI platforms in India typically charge ₹5–₹25 per minute all-in, depending on the provider stack (STT, LLM, TTS, telephony) and whether pricing is flat or component-based. Bolti charges a flat ₹7/min covering the full pipeline with no hidden fees.
Is voice AI fully free?
No voice AI platform is free at production scale — every call uses real compute and telephony infrastructure. Most platforms offer a limited free trial. Bolti gives new accounts 50 free minutes, which is enough to build and test a working agent before committing any budget.
What is the 30% rule in AI?
The 30% rule is an informal benchmark suggesting that AI automation should reduce operational costs by at least 30% to justify the switch from human agents. For voice AI, the math often exceeds this: a human call-centre agent in India costs ₹80–₹150 per handled call all-in, while a voice AI call at 90 seconds costs roughly ₹10.50 at ₹7/min.
What hidden fees should I watch for in voice AI pricing?
Common hidden fees include per-call connection charges, phone number rental fees, concurrency surcharges, premium TTS voice add-ons, and higher rates for outbound vs. inbound calls. Always ask whether the advertised per-minute rate covers STT, LLM, TTS, and telephony together or just one layer.
How much does audio AI (TTS) cost on its own?
TTS-only pricing from providers like ElevenLabs or Cartesia typically runs ₹0.30–₹2 per minute of synthesized audio, depending on voice quality and model. When you use a full voice AI platform like Bolti, TTS cost is bundled into the flat per-minute rate rather than billed separately.