How voice AI platforms price: ThunderPhone vs. Retell vs. Vapi vs. Bland

Voice AI platforms quote per-minute prices, but the prices do not describe the same thing. One vendor's headline rate is a complete call price; another's is an infrastructure line item that grows once a language model and voice are attached; a third's is a hosting fee that by design excludes the speech, model, and voice components; a fourth's is a bundled rate gated behind daily-call and concurrency limits. A buyer who compares the four headline numbers directly will rank the platforms incorrectly.

This guide explains each pricing model in its own terms, then normalizes all four against one explicit workload. ThunderPhone figures reflect its published rates as of August 19, 2026; every Retell, Vapi, and Bland figure was checked against that vendor's public pricing page or documentation on August 5, 2026 and re-checked on August 18, 2026, with the source linked next to the claim. This is a neutral buyer's guide, and none of the arithmetic below is a quote.

Four pricing models, briefly

ThunderPhone: all-in engine rates

ThunderPhone prices the complete engine — speech recognition, language model, and voice — as one per-minute rate: Spark at 2¢/minute, Bolt at 5¢/minute, and Storm at 9¢/minute, pay as you go with no subscription or seat fee. Premium voice or language paths can add 2–3¢/minute (up to 3¢), and optional add-ons carry published surcharges: verbal acknowledgements +2¢ and call supervision +8¢ (both Storm only), long prompts +1–2¢/minute per additional 10K tokens after the first 5K, and demo numbers +1¢/minute plus $1/month. Hold time bills a flat 2¢/minute on every engine; voicemail and phone-menu minutes bill at the engine rate, with straight-to-voicemail calls capped at one minute. The builder displays the current all-in rate for the exact configuration, and telephony charges depend on setup.

Retell AI: component pricing with an advertised all-in range

Retell prices components separately: voice infrastructure at $0.055/minute, language models from $0.003 to $0.16/minute depending on the model, text-to-speech at $0.015–$0.040/minute by provider, standard telephony at $0.015/minute (varies by country), and phone numbers at $2/month. The advertised all-in range is $0.07–$0.31/minute depending on the language model and add-ons. Optional add-ons stack on top: knowledge base, denoising, and guardrails at $0.005/minute each, PII removal at $0.01/minute, and AI quality assurance at $0.10/minute after the first 100 free minutes. There is no mandatory subscription on pay as you go; 20 concurrent calls are included and added concurrency is $8 per concurrent call per month. Retell pricing, accessed 2026-08-18.

Vapi: hosting fee plus provider pass-through

Vapi's Build plan lists call hosting at $0.05/minute. Speech recognition, language models, and text-to-speech bill at provider cost on top — or show as $0 on the Vapi bill when customers bring their own API keys, in which case the providers bill them directly. Telephony is separate. Ten concurrent calls are included, with extra lines at $10 each per month; the Scale plan uses a fixed platform fee with committed volume and custom terms. Compliance is also an add-on: HIPAA at $2,000/month and zero data retention at $1,000/month. The critical point: $0.05/minute is not a call price — it is the hosting portion of one. Vapi pricing, accessed 2026-08-18.

Bland AI: tiered bundles with platform fees and limits

Bland prices an all-inclusive talk minute — the rate covers the language model, speech recognition, and text-to-speech with no token charges or model-provider pass-through — but the rate and its operational allowances vary by tier. Start is $0.14/minute with no platform fee, limited to 100 calls/day and 10 concurrent calls; Build is $0.12/minute plus $299/month with 2,000 calls/day and 50 concurrent; Scale is $0.11/minute plus $499/month with 5,000 calls/day and 100 concurrent; Enterprise is custom. Transfer minutes bill separately at $0.05/$0.04/$0.03 by tier (waived for bring-your-own-telephony customers), and built-in telephony is at pass-through cost. Bland pricing, accessed 2026-08-18.

At a glance

One workload, four bills

Use one explicit workload: 2,000 calls per month × 5 connected minutes = 10,000 connected minutes, spread evenly, peaking at no more than 10 simultaneous calls. Assume one primary included language, ordinary connected talk time, one phone number, no transfer minutes, and no voicemail, hold, or screening minutes. This is illustrative usage arithmetic, not a quote from any vendor.

ThunderPhone — the engine rate is the complete base-engine usage price:

• Spark: 10,000 × $0.02 = $200/month
• Bolt: 10,000 × $0.05 = $500/month
• Storm: 10,000 × $0.09 = $900/month
• A premium voice or language path at the maximum 3¢/minute would add up to $300/month; telephony is setup-dependent and not added here. Subscription: $0.

Retell AI — the advertised all-in range applied to the workload:

• Low end: 10,000 × $0.07 = $700/month
• High end: 10,000 × $0.31 = $3,100/month

Where the workload lands in that range depends on the selected language model and add-ons, and the separately listed telephony ($0.015/minute) and number ($2/month) charges may not be represented at every point in the range, so the exact configured total is not knowable from public pricing alone. Notably, ThunderPhone's Storm at $900 falls inside Retell's advertised range, while Spark ($200) and Bolt ($500) land below its $700 floor. Retell pricing, accessed 2026-08-18.

Vapi — the public arithmetic covers hosting only:

• Call hosting: 10,000 × $0.05 = $500/month — before speech, model, voice, and telephony costs, which pass through at provider rates or bill directly under your own API keys.

The complete total is $500 + provider costs + telephony and cannot be computed from the public page. It is worth pausing on the coincidence: ThunderPhone's Bolt all-in rate (5¢) equals Vapi's hosting-only fee ($0.05) — one is a complete engine rate, the other is the platform's share of an incomplete total. The 10-call peak stays within Vapi's 10 included concurrent calls, so no extra lines are needed. Vapi pricing, accessed 2026-08-18.

Bland AI — the scenario averages about 67 calls/day and peaks at 10 concurrent, so it fits Start's published limits if traffic actually distributes that way:

• Start: 10,000 × $0.14 + $0 = $1,400/month
• Build: 10,000 × $0.12 + $299 = $1,499/month
• Scale: 10,000 × $0.11 + $499 = $1,599/month

The higher tiers cost more at this volume because their platform fees outweigh their lower per-minute rates; what they buy is headroom, not savings. Built-in telephony is pass-through and is not added here. Bland pricing, accessed 2026-08-18.

Summary for this scenario: ThunderPhone $200–$900 by engine; Retell $700–$3,100 advertised all-in; Vapi $500 hosting before pass-through; Bland $1,400 on its cheapest eligible tier. Rerun the arithmetic with your own call length, language, and configuration before drawing a conclusion — average call length alone can reorder these results.

What a "minute" includes

The same word covers different bundles:

• ThunderPhone: the engine rate includes speech recognition, the language model, and the voice. Premium voice or language paths (+2¢ or +3¢/minute) and published add-on surcharges are the exceptions, shown in the builder as a current all-in rate. Hold bills a flat 2¢/minute; voicemail and phone-menu minutes bill at the engine rate, straight-to-voicemail capped at one minute.
• Retell: the $0.055/minute infrastructure rate includes none of the model or voice cost; each is its own line item, as are telephony and the optional per-minute add-ons. Only the $0.07–$0.31 all-in range approximates a complete minute. Retell pricing, accessed 2026-08-18.
• Vapi: the $0.05/minute hosting fee includes none of the speech, model, or voice cost by design — those pass through at cost, or move onto your own provider bills with your own API keys. Vapi pricing, accessed 2026-08-18.
• Bland: the talk-minute rate includes the language model, speech recognition, and text-to-speech, with no token charges. Transfer minutes bill separately by tier, and telephony is pass-through. Bland pricing, accessed 2026-08-18.

Hidden-cost checklist for buyers

Before signing anything, price these against your actual traffic:

1. Non-talk minutes. Hold, voicemail, phone-menu navigation, and transfer time can bill differently from conversation. ThunderPhone publishes hold at a flat 2¢/minute and caps straight-to-voicemail billing at one minute; Bland bills transfer minutes at separate tiered rates. Ask every vendor how each call state bills.
2. Telephony. Carrier minutes and phone numbers are usually outside the headline rate — Retell lists $0.015/minute and $2/number/month, Bland's built-in telephony is pass-through, Vapi prices it separately, and ThunderPhone's is setup-dependent. Retell pricing and Bland pricing, accessed 2026-08-18.
3. Concurrency and volume caps. Retell includes 20 concurrent calls ($8 each beyond), Vapi includes 10 ($10/line beyond), and Bland caps calls/day and concurrency by tier — a spike can force a tier upgrade that costs more than the minutes. Retell pricing, Vapi pricing, and Bland pricing, accessed 2026-08-18.
4. Platform and compliance fees. Bland's Build and Scale tiers carry $299 and $499 monthly fees; Vapi lists HIPAA at $2,000/month and zero data retention at $1,000/month. ThunderPhone and Retell list no mandatory subscription on pay as you go. Vapi pricing and Bland pricing, accessed 2026-08-18.
5. Quality and feature add-ons. Per-minute surcharges compound: Retell's knowledge base, denoising, guardrails, PII removal, and AI quality assurance each add to the rate; ThunderPhone's verbal acknowledgements, call supervision, and long-prompt surcharges are published per minute. Price the configuration you will actually run.
6. Testing minutes. Simulated and test calls are often billable real calls — ThunderPhone shows the charge before a run, and Vapi's docs state test-suite calls bill like regular calls. Budget for a regression suite, not just production traffic. Vapi Test Suites, accessed 2026-08-18.
7. Who bills you. Bringing your own API keys to Vapi moves provider costs off Vapi's invoice onto the providers' — it changes who bills, not necessarily what the workload costs. Vapi pricing, accessed 2026-08-18.

FAQ

Which platform is cheapest for 10,000 connected minutes per month?

In this defined included-language scenario, ThunderPhone's published arithmetic is lowest. Its engines calculate to $200–$900; Retell's advertised all-in range is $700–$3,100; Vapi's knowable public figure is $500 for hosting alone, before provider and telephony costs; Bland's cheapest eligible tier is $1,400. Different call lengths, languages, and add-ons can change the ordering, so rerun the arithmetic with your own configuration. Retell pricing, Vapi pricing, and Bland pricing, accessed 2026-08-18.

Why can't I just compare the headline per-minute rates?

Because they price different bundles. ThunderPhone's 5¢ Bolt rate is a complete engine price, while Vapi's $0.05 hosting fee excludes speech, model, voice, and telephony; Retell's $0.055 infrastructure rate similarly excludes the model and voice that its $0.07–$0.31 all-in range adds back. Normalize to a complete configured minute before comparing. Retell pricing and Vapi pricing, accessed 2026-08-18.

Which platforms charge a monthly platform fee?

Bland's Build and Scale tiers do ($299 and $499/month); ThunderPhone, Retell pay-as-you-go, and Vapi's Build plan list no mandatory subscription. Vapi's Scale plan uses a fixed platform fee with committed volume, and compliance add-ons (HIPAA $2,000/month, zero data retention $1,000/month) function like recurring fees where required. Bland pricing and Vapi pricing, accessed 2026-08-18.

How do voicemail, hold, and transfer minutes bill?

Differently on each platform, and the details matter at volume. ThunderPhone bills hold at a flat 2¢/minute and voicemail and phone-menu minutes at the engine rate, with straight-to-voicemail calls capped at one minute. Bland bills transfer minutes at $0.05/$0.04/$0.03 by tier, waived for bring-your-own-telephony customers. The reviewed Retell and Vapi public pages do not itemize these states, so ask directly. Bland pricing, accessed 2026-08-18.

Does bringing my own API keys make Vapi cheaper?

It makes Vapi's invoice smaller, not necessarily the workload cheaper. Vapi lists speech, model, and voice as $0 on its bill when customers bring their own keys, but usage under those keys is billed by the providers at their rates. The comparison that matters is total spend across all invoices for the same configured call. Vapi pricing, accessed 2026-08-18.

What should I check before trusting any of these numbers?

The vendor's live pricing page, against your own traffic profile. Voice AI pricing changes frequently; every third-party figure here is a point-in-time reading with its accessed date attached, the scenario assumes an even traffic distribution that real workloads may not match, and setup-dependent charges such as telephony are excluded. Reproduce the arithmetic from current sources before deciding.

Sources and freshness

All third-party rates on this page were checked against the linked vendor pricing pages on the accessed dates shown beside each figure. ThunderPhone pricing and product details reflect its published pricing and documentation as of August 19, 2026. Vendors change pricing often, so confirm against the live vendor pages before relying on any figure here.