What is it
Per-interaction pricing is a billing unit where each patient-agent or user-agent interaction is metered, common in healthcare AI and customer engagement platforms.
The term “interaction” sits between the granularity of a single message and the finality of a resolved ticket. An interaction is a bounded engagement — one patient phone call, one support session, one workflow run — that begins and ends regardless of whether the AI produced the outcome the buyer hoped for. That makes it intuitive to operational buyers (healthcare administrators, contact-center managers) who already count interactions in their SLAs, and it sidesteps the definitional disputes of outcome-based billing.
Hippocratic AI uses the interaction as the basis for a per-agent-hour staffing model: health systems pay roughly $9 per hour of active patient-interaction time — benchmarked against the ~$39/hour median wage of a registered nurse. Uniphore layers a per-interaction consumption charge on top of a platform license and per-seat fee, so the meter captures volume growth independent of headcount. Yellow.ai bundles interactions and sessions on its Free tier (1 AI agent, 500 chat sessions/month) before customers commit to its outcome-based $0.99-per-resolution overage.
That flexibility is also the definitional challenge. “Interaction” is deliberately broad — a real-time voice call of any duration, a multi-turn chat session, or a structured workflow run — and vendors draw the boundary differently. Confirm exactly what starts and ends an interaction in any contract before modelling spend.
How it works
The interaction meter works by detecting a defined trigger event (a patient calling in, a customer opening a chat, an employee initiating a workflow) and counting that as one unit. The meter closes on a corresponding end signal: the call terminates, the chat session times out, or the workflow reaches a terminal state. Everything that happens in between — messages exchanged, tokens consumed, tools invoked — is absorbed into the flat per-interaction charge.
| Dimension | What it controls | Example |
|---|---|---|
| Interaction definition | What counts as “one” interaction — a call, a session, a workflow run | Hippocratic AI: one agent-patient call of any duration |
| Duration handling | Whether time within the interaction affects the charge | Hippocratic AI bills per agent-hour, so longer calls cost more within the same interaction frame |
| Outcome linkage | Whether the interaction must succeed to be billable | Yellow.ai charges per resolution (a successful close), not per raw interaction |
| Volume tiers | Whether the per-interaction rate is negotiated at scale | Uniphore negotiates per-interaction consumption inside custom enterprise contracts |
| Channels | Whether voice, chat, email, and SMS interactions carry different rates | Maven AGI scopes voice and chat separately; voice typically carries a premium over chat |
Unit math: For a flat per-interaction model —
Total bill = interaction_count × per_interaction_rate. For Hippocratic AI’s time-weighted variant —Total bill = total_active_agent_hours × hourly_rate, wheretotal_active_agent_hours = sum of all interaction durations in hoursandhourly_rate ≈ $9.
The per-interaction model diverges from per-token or per-API-call billing by absorbing backend complexity. A patient call might trigger dozens of LLM inferences, several EHR lookups, and a post-call summary; per-interaction pricing presents one invoice line. That abstraction is a selling point in regulated industries where the buyer (a hospital CTO, a bank’s operations team) does not want to reason about token consumption. See the introduction to usage-based pricing for the framework, and choosing the right usage metric for when interaction-level meters outperform token- or output-based ones.
Companies using this
Four corpus companies use interactions as a primary or secondary billing unit, spanning healthcare AI (Hippocratic AI), customer-support automation (Maven AGI, Yellow.ai), and enterprise conversational AI (Uniphore). The cluster reflects where agent-human exchanges carry enough compliance and quality weight to make the interaction a natural billing anchor.
| Company | Product | Pricing model | Billing units | Free tier | Verified |
|---|---|---|---|---|---|
| Hippocratic AI | Safety-focused healthcare LLM — patient-facing AI agents for non-diagnostic clinical tasks | No | 2026-06-10 | ||
| Maven AGI | Enterprise AI agent platform for customer support | No | 2026-07-21 | ||
| Observe.AI | Agentic CX platform — contact-center AI agents, conversation intelligence & auto-QA | No | 2026-07-23 | ||
| Uniphore | Business AI Cloud — enterprise conversational AI & agentic automation | No | 2026-06-09 | ||
| Yellow.ai | Conversational CX automation platform | Yes | 2026-06-11 |
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FAQ
What is per-interaction pricing?
Per-interaction pricing is a billing unit where each discrete exchange between an AI agent and a human — a patient call, a support conversation, or an employee workflow session — is counted and charged as one interaction. Unlike per-message billing (which meters individual turns) or per-resolution billing (which requires a verified outcome), an interaction is typically a bounded engagement with a clear start and end, regardless of how many turns it contains or whether it resolves successfully.
How does per-interaction pricing differ from per-resolution pricing?
Per-resolution pricing charges only when the AI closes a ticket without escalation — you pay for successful outcomes. Yellow.ai, for example, charges $0.99 per resolution after 500 free sessions. Per-interaction pricing charges for the engagement itself regardless of outcome: Hippocratic AI meters patient interactions as active agent-hours, and Uniphore layers a per-interaction consumption charge on top of its platform license. The distinction matters for buyers: per-interaction costs accrue on every attempt, while per-resolution pricing puts some financial risk on the vendor to deliver a result.
Which companies use per-interaction pricing?
In this corpus, four companies meter interactions as a primary or secondary billing unit: Hippocratic AI (~$9 per active agent-hour of patient interaction), Uniphore (a per-interaction consumption charge on top of a platform license and per-seat fee), Yellow.ai (interactions and sessions on its Free tier), and Maven AGI (contracts scoped to conversation and resolution volume across chat and voice).
How is an interaction different from a message or a session?
A message is a single turn — one prompt or one reply. An interaction is the whole bounded engagement that a set of messages belongs to: one patient phone call, one support chat session, or one workflow run. Because the boundary is defined by the vendor, buyers should confirm exactly what starts and ends an interaction — a call of any duration, a chat that times out, or a completed workflow — before modelling spend.
Related billing units
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- Token-Based PricingA billing unit common in LLM and AI products, where customers are charged per input and output token processed.
- Per-Seat PricingA billing unit where the vendor charges a fixed fee per named user, regardless of how much each user consumes.
- Per-Resolution PricingA billing unit unique to AI customer-support products, where the vendor charges only when an AI agent resolves a customer issue without escalation.
- Bandwidth-Based PricingA billing unit where customers are charged per gigabyte of data transferred out of the platform.
- Per-Function-Invocation PricingA billing unit where customers are charged per serverless function invocation, often combined with a separate compute-time charge.
- CPU-Hour PricingA billing unit where customers are charged for the CPU time their workloads consume, typically measured in vCPU-seconds or vCPU-hours.
- GB-Hour PricingA billing unit where customers are charged for the memory their workloads consume over time, measured in gigabyte-hours.
- GPU-Hour PricingA billing unit where customers are charged for GPU time consumed, typically measured per-second or per-hour by GPU type.
- Per-API-Call PricingA billing unit where customers are charged per API request, regardless of payload size or processing time.
- Per-GB Storage PricingA billing unit where customers are charged per gigabyte of data stored on the platform per month.
- Media-Minute PricingA billing unit where customers are charged per minute of audio or video processed — used by speech, voice, and video AI vendors.
- Per-Request PricingA billing unit where customers are charged per request served — the generic meter for inference endpoints, search, scraping, and browser infrastructure.
- Per-Event PricingA billing unit where customers are charged per event ingested — the native meter of observability and billing-infrastructure platforms.
- Vector Storage PricingA billing unit where customers are charged for vectors stored or indexed — the storage dimension of vector database pricing.
- Per-Character PricingA billing unit where customers are charged per character of text processed — the standard meter for text-to-speech and translation.
- Per-Document PricingA billing unit where customers are charged per document processed or generated — common in AI writing, SEO, and document-intelligence tools.
- Per-Page PricingA billing unit where customers are charged per page crawled, parsed, or rendered — the meter for web scraping and document parsing.
- Per-Transaction PricingA billing unit where customers are charged per financial or billing transaction processed — the meter of billing and accounting platforms.
- Active-User PricingA billing unit where customers are charged per monthly or daily active user rather than per provisioned seat.
- Per-Task PricingA billing unit where customers are charged per task an automation or agent executes — Zapier's historical unit, now spreading to AI agents.
- Per-Unit PricingA billing unit used by robotics, hardware AI, and some SaaS companies where the metered object is a physical or abstract 'unit' — a robot deployed, a device sold, or a defined deliverable.
- Workflow Execution PricingA billing unit where each end-to-end workflow or automation run is metered and billed, regardless of the compute steps it contains.
- Per-Message PricingA billing unit where each individual message or reply in a conversation is metered, common in AI chat and voice platforms.
- Per-Invoice PricingA billing unit used by billing infrastructure platforms where each invoice generated or processed is metered as the primary cost driver.
- Per-Action PricingA billing unit where each discrete action taken by an AI agent or automation is metered — common in browser automation and agentic workflow tools.
- Per-Image PricingA billing unit where each AI-generated image is metered, common in image generation APIs and multimodal AI platforms.
- Per-Conversation PricingA billing unit where each complete customer conversation — from first message to resolution — is metered as a single chargeable event.
- Per-Record PricingA billing unit where each data record processed, labeled, or extracted is metered — common in data platforms and web scraping services.
- Per-Word PricingA billing unit common in translation and localization platforms where the metered object is the word count of content processed.
- Per-Video PricingA billing unit where each AI-generated video is metered, common in video generation and synthetic media platforms.
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- Per-Datapoint PricingA billing unit where each individual data measurement or signal ingested is metered — common in cloud cost intelligence and ML evaluation platforms.
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- Robot-Hour PricingA billing unit where each hour a robot or autonomous system operates is metered — the robotics equivalent of a GPU-hour.
- Per-Contact PricingA billing unit where each contact or lead in the database is metered, common in AI sales development and outbound automation platforms.
- Per-Mailbox PricingA billing unit where each connected email mailbox or sending account is metered, common in AI outbound sales and email automation platforms.
- Browser-Hour PricingA billing unit where each hour of headless browser compute time is metered, common in web scraping and browser automation platforms.
- Per-Generation PricingA billing unit where each AI-generated creative asset — image, video, or design — is counted as a 'generation' and metered accordingly.
- Per-Ticket PricingA billing unit where each customer support ticket handled by an AI agent is metered — common in AI customer service platforms.
- Per-Log PricingA billing unit where each LLM request log ingested or stored is metered — common in AI observability and evaluation platforms.
- Per-Trace PricingA billing unit where each distributed trace — a complete record of an LLM request chain — is metered, common in AI observability platforms.
- Per-IP PricingA billing unit where each IP address or proxy endpoint allocated is metered — used by web scraping proxy providers.
- Per-Device PricingA billing unit where each hardware device or endpoint connected to the AI platform is metered.
- Per-Case PricingA billing unit used in legal AI platforms where each case or matter processed by the AI is metered.
- Per-Report PricingA billing unit where each AI-generated report or analysis document is metered as a discrete output.