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Comparison LabCompare 27 voice AI platforms and components across seven buying contexts, with sourced capabilities, current price captures and visible unknowns.Voice AI Price Index: prices, evidence and historyUnderstand the complete voice-agent cost stack: models, voice, transcription, telephony, subscriptions, capacity and add-ons.Know the cost before the first callEstimate monthly voice-agent costs, AI minutes, setup expenses and volume scenarios using your own transparent assumptions.AI voice agents for dentalAppointments, rescheduling and after-hours calls—with a person ready for clinical questions. Explore call flows, safe automation, integrations, tests and cost considerations.

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AssemblyAI vs Hermes

AssemblyAI is positioned as transcription APIs for live and recorded audio, with model-specific language and analysis options. Hermes is positioned as an agency operations layer bundling voice providers, client workspaces and bill

The decision in context

AssemblyAI is positioned as transcription APIs for live and recorded audio, with model-specific language and analysis options. Hermes is positioned as an agency operations layer bundling voice providers, client workspaces and billing. Start by deciding who owns the missing layers, then inspect the documented differences below.

STT and Full Platforms are different product categories. An underlying engine or framework is not a complete substitute for a deployed agent workflow.

6 jointly documented catalog fields. This measures evidence coverage, not equivalent quality or an overall winner.

Compare for the job

Test opening hours, booking conflicts and an unanswered transfer.

2 of 4 slots
AssemblyAIHermes
Decision signals / differences first

Start where the records differ.

6 of 8 priority fields differ

Values and evidence states are compared together. Shared facts follow the differences; Unknown never means No.

Selected platforms: buyer-critical differences before detailed dimensions
Decision pointAssemblyAIHermes
Billing modelDifferent records
component-stackVerified Yes · 2026-09-28
monthly-bundleVerified Yes · 2026-09-28Documented product/configuration only; see research notes · Private beta; Starter
Billing unitDifferent records
Async audio hours; streaming connection hours; agent session minutes; gateway tokensVerified Yes · 2026-09-28
monthVerified Yes · 2026-09-28Documented product/configuration only; see research notes · Private beta; Starter
Bring your telephonyDifferent records
YesVerified Yes · 2026-09-28
UnknownUnknown after research · 2026-09-28Documented product/configuration only; see research notes
Bring your modelDifferent records
YesVerified Yes · 2026-09-28
UnknownUnknown after research · 2026-09-28Documented product/configuration only; see research notes
HIPAA pathDifferent records
YesConditional · 2026-09-28Contract-covered AssemblyAI services · Sales-confirmed agreement
UnknownUnknown after research · 2026-09-28Documented product/configuration only; see research notes
WebhooksDifferent records
YesConditional · 2026-09-28Unknown
YesVendor claim · 2026-09-28API / webhookDocumented product/configuration only; see research notes
Your requirements & next steps
Carried from your shortlist

Your requirements

Edit requirements →

Ready-made / AI receptionist · Strict evidence mode

No personal requirements yet. Add criteria in Advanced Filter to prioritize this comparison.

Unknown ≠ No
Evidence, side by sideNo benchmark scores
HermesFull Platforms
Pricing model
AssemblyAI
component-stackVerified Yes · 2026-09-28

STT hours/session duration, agent minutes, gateway tokens and add-ons remain distinct.

Hermes
monthly-bundleVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Headline / base price
AssemblyAI
Universal-2 async / Universal-Streaming $0.15/hour; U3.5 Pro async $0.21/hour; U3 realtime $0.45/hour; Voice Agent $0.075/minVerified Yes · 2026-09-28

Model rates are scoped; add-ons stack; reference states updated May 29, 2026 and conflicts are retained.

Hermes
Starter $149/monthVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Billing unit
AssemblyAI
Async audio hours; streaming connection hours; agent session minutes; gateway tokensVerified Yes · 2026-09-28

Idle streaming connection duration is billable. No fabricated all-in phone cost per minute.

Hermes
monthVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Platform fee
AssemblyAI
No base monthly subscription on PAYG; SSO add-on is separately monthlyVerified Yes · 2026-09-28

SSO costs $199 per connection per month; do not mistake no base fee for no fixed optional charges.

Hermes
Starter $149; Business $399; Agency $699/month; Enterprise customVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Included usage
AssemblyAI
New-account $50 credits for listed speech APIs; LLM Gateway excludedVerified Yes · 2026-09-28

Not a fixed monthly audio allowance; credits do not expire.

Hermes
Starter 300; Business 1,000; Agency 1,650 minutesVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Overage
AssemblyAI
PAYG rates after credits; access pauses at exhausted balance without fundingVerified Yes · 2026-09-28

No invented bundle overage.

Hermes
UnknownConflicting evidence · 2026-09-28

Official overage rates conflict, messaging pass-through varies and beta account terms need confirmation.

Documented product/configuration only; see research notes · Private beta; Starter
Pass-through costs
AssemblyAI
Twilio carrier; optional custom/Gateway LLM; standalone STT add-ons and per-channel billingVerified Yes · 2026-09-28

Component choices and call mix must be specified.

Hermes
A2P messaging pass-through and customer billing configuration varyVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Free offer
AssemblyAI
UnknownNot researched

Not yet researched against this buyer-critical field standard.

Hermes
UnknownUnknown after research · 2026-09-28

Official overage rates conflict, messaging pass-through varies and beta account terms need confirmation.

Private beta; Starter
Complete cost ceiling
AssemblyAI
UnknownUnknown after research · 2026-09-28

No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary.

Hermes
UnknownUnknown after research · 2026-09-28

Official overage rates conflict, messaging pass-through varies and beta account terms need confirmation.

Documented product/configuration only; see research notes · Private beta; Starter
What remains unresolved
AssemblyAI
UnknownUnknown after research · 2026-09-28

No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary.

Hermes
Official overage rates conflict, messaging pass-through varies and beta account terms need confirmation.Verified Yes · 2026-09-28

Research conclusion about cost completeness, not a vendor capability.

Documented product/configuration only; see research notes · Private beta; Starter

Anyone with this link can view the encoded decision criteria.

Vendor documentation establishes a claim. Public model benchmarks are separate context, not measurements of these platforms.

Open saved comparison ↗

What to verify together.

AssemblyAI

A transcription hour is not a complete agent hour.

Universal-2 async / Universal-Streaming $0.15/hour; U3.5 Pro async $0.21/hour; U3 realtime $0.45/hour; Voice Agent $0.075/min · V3.3 evidence review · Voice Agent API reference; standalone STT is hourly; transport/add-ons separate

Excluded / confirm: Complete cost cannot be established from this reference. No complete phone bill ceiling from minutes alone; carrier, model and addon scope vary. · Twilio carrier; optional custom/Gateway LLM; standalone STT add-ons and per-channel billing

component-stackVerified Yes · 2026-09-28

STT hours/session duration, agent minutes, gateway tokens and add-ons remain distinct.

Read the complete profile →

Hermes

The service is advertised as a private beta with public launch pending.

Starter $149/month · V3.3 evidence review · Starter private beta subscription; unresolved overage scope

Excluded / confirm: Complete cost cannot be established from this reference. Official overage rates conflict, messaging pass-through varies and beta account terms need confirmation. · A2P messaging pass-through and customer billing configuration vary

monthly-bundleVerified Yes · 2026-09-28

Reviewed current public offer; retain original billing scope and units.

Documented product/configuration only; see research notes · Private beta; Starter
Read the complete profile →

The evidence overlap.

Both records have documented values for Product type, Pricing model, Published numeric pricing, Twilio, Checked within 30 days, Retained price snapshot. Matching availability does not measure behavior under your call conditions.

Run the same booking, tool failure and unsuccessful human-transfer cases. Record both outcomes and billable units before signing a deployment agreement.

Build a buyer-operated pilot →

Editorial index gate: noindex-cross-category. Different product layers. This pair is useful for architecture inspection, not a like-for-like purchase ranking.