How to Estimate Voice AI Cost Per Minute in India
Bolti, a voice AI platform for production phone agents, charges ₹7/min on a pay-as-you-go basis — with no monthly minimums and a 50-minute free trial to validate your use case first. Before you sign any contract, here's how to project what you'll actually spend.
What drives voice AI cost per minute in India?
Voice AI cost per minute is not a single number — it's a stack of four components that run simultaneously on every call. Understanding each one lets you model your bill accurately instead of being surprised at month-end.
Every call passes through:
- STT (Speech-to-Text): Transcribes the caller's audio into text. Providers like Deepgram, Fennec (optimised for Hindi, Tamil, Telugu), and Azure each have different per-minute rates.
- LLM (Large Language Model): Reads the transcript and decides what to say. Billed by tokens — longer prompts and longer conversations cost more.
- TTS (Text-to-Speech): Synthesises the agent's voice. Billed by characters generated.
- Telephony: The PSTN/SIP leg of the call. Varies by carrier, trunk, and whether you bring your own (BYOC via Twilio, Plivo, Exotel) or use Bolti numbers.
On Bolti, the platform fee wraps these into a single ₹7/min rate for most configurations. Your variable costs come from the providers you choose and your call volume.
How to calculate your monthly voice AI spend
Use this five-step framework. It takes about 15 minutes with a spreadsheet.
Step 1 — Estimate total call minutes per month
Start with your call volume, not your agent count.
- How many outbound calls do you plan to make (or inbound calls to handle)?
- What is the average call duration? For payment reminders, typically 1–3 minutes. For support or appointment booking, 3–7 minutes.
- Multiply: calls/month × avg duration = total minutes/month
Example: 2,000 outbound payment reminder calls at 2 minutes average = 4,000 minutes/month.
Step 2 — Apply the platform rate
At ₹7/min, 4,000 minutes = ₹28,000/month in platform fees. That's your baseline.
If you're running higher volumes — say, 50,000+ minutes/month — talk to the team about volume rates before assuming the pay-as-you-go number scales linearly.
Step 3 — Factor in provider choices
Your STT, LLM, and TTS providers are billed separately by those vendors (or bundled depending on your Bolti plan). The key levers:
- Indian-language calls: Fennec or Azure STT will give better accuracy for Hindi, Marathi, Tamil, Telugu — but check their per-minute rates against Deepgram.
- LLM model tier: GPT-4o costs more per token than GPT-4o-mini. For simple scripts (payment reminders, appointment confirmations), a lighter model is usually sufficient.
- TTS provider: ElevenLabs voices sound premium but cost more per character than some alternatives. For high-volume outbound, the difference adds up.
A rough rule: provider costs typically add 20–40% on top of the platform minute rate for a mid-complexity agent.
Step 4 — Account for retries and no-answers
Batch campaigns retry unanswered calls. If your retry budget is 3 attempts per contact and your connect rate is 40%, you're effectively dialling 2.5× your connected call count.
- 2,000 contacts × 2.5 dial attempts × 0.5 min avg ring time = 2,500 extra minutes before a human even picks up.
- On Bolti, calls that don't connect still consume telephony seconds. Model this or you'll underestimate by 30–50%.
Step 5 — Add a buffer for testing and iteration
Every new agent needs tuning. Budget 500–1,000 minutes for prompt iteration, voice selection (you can preview voices before committing in the Voice tab), and QA calls before going live. At ₹7/min, that's ₹3,500–₹7,000 — a small insurance policy against a broken script reaching 10,000 contacts.
Sample cost models for common Indian use cases
These are illustrative estimates, not guarantees. Your actual numbers depend on provider mix, call duration, and connect rates.
| Use case | Calls/month | Avg duration | Est. platform cost (₹7/min) |
|---|---|---|---|
| Payment reminders (NBFC) | 5,000 | 2 min | ₹70,000 |
| Appointment booking (clinic) | 1,000 | 4 min | ₹28,000 |
| HR screening (BPO) | 500 | 8 min | ₹28,000 |
| After-hours support (SaaS) | 3,000 inbound | 5 min | ₹1,05,000 |
For the NBFC example, adding provider costs at ~30% overhead brings the total to roughly ₹91,000/month — or about ₹18 per connected call. Compare that to a human agent's fully-loaded cost per call.
What affects cost that most estimates miss
Three things ops leaders consistently undercount:
- Silence and hold time. If your IVR plays a 30-second hold message before the agent speaks, that's billed time. Design your agent flow to minimise dead air.
- Long system prompts. Every LLM call includes your system prompt. A 2,000-token prompt on a 10-minute call means 20+ LLM calls — each carrying that overhead. Trim prompts ruthlessly.
- Multilingual routing. If you detect language mid-call and switch STT providers (e.g. from Deepgram to Fennec for a Hindi caller), you may incur initialisation overhead. Test this in staging.
For a deeper look at how provider choices interact with latency and quality — not just cost — see the Bolti use cases overview for examples across industries.
Build your estimate on the Bolti pricing page
Ready to run the numbers for your specific volume? The Bolti pay-as-you-go pricing page shows the ₹7/min rate, what's included, and where volume discounts apply. Start with the free trial — 50 minutes at no cost — to validate your average call duration and connect rate before projecting a full month. That real data will make your estimate far more accurate than any spreadsheet assumption.
If your projected volume is above 30,000 minutes/month or you need an on-premises or enterprise contract, talk to the Bolti team before committing to pay-as-you-go.
Frequently Asked Questions
What is the voice AI cost per minute in India on Bolti?
Bolti charges ₹7 per minute on a pay-as-you-go basis, with no monthly minimums. This covers the platform fee. STT, LLM, and TTS provider costs are additional and depend on which providers you configure for your agent.
How do I estimate my total monthly voice AI spend?
Multiply your expected calls per month by average call duration to get total minutes. Apply ₹7/min for the platform cost, then add 20–40% for STT, LLM, and TTS provider fees. Also account for retry dials on unanswered calls, which can add 30–50% to your raw dial count.
Does Bolti charge for calls that don't connect?
Telephony seconds are typically consumed even for unanswered calls during the ring phase. When modelling batch campaign costs, factor in your expected connect rate and retry budget to avoid underestimating total minutes.
Are there volume discounts for high-minute usage?
Bolti's standard rate is ₹7/min pay-as-you-go. For workloads above roughly 30,000 minutes per month, it's worth contacting the Bolti team directly to discuss volume pricing before assuming the per-minute rate applies at scale.
Which STT provider should I use for Hindi or other Indian language calls?
Bolti supports Fennec, which is optimised for Indian languages including Hindi, Tamil, and Telugu. For English-primary calls, Deepgram is the recommended default. Your STT choice affects both accuracy and per-minute cost, so test both in your free trial minutes.