Sierra

Sierra sells to enterprises that want an AI agent to run the front line rather than sit beside one, and need the compliance file settled first. It holds ISO 27001 and ISO/IEC 42001, the AI management standard, plus FedRAMP High, PCI DSS Level 1 and HIPAA.

The agent covers voice, chat, email and WhatsApp in 59 languages, and connects to systems of record so it acts rather than only answers. Billing is per outcome, which Sierra defines as "a resolved support conversation, a saved cancellation, an upsell, a cross-sell". There is no seat to buy: "With no reliance on seat-based pricing, we have no conflicting incentives". Routing and greeter-style interactions can be priced per conversation instead.

What Sierra does not do is publish a number. There is no pricing page: sierra.ai/pricing returned HTTP 404 on 5 September 2026, and no plan, minimum, allowance or overage appears anywhere on the site. The criteria that decide whether an outcome bills are "agreed-upon" per customer and never published, so one Sierra contract cannot be compared against another, let alone a rival's rate. Escalations are free only "in most cases", and the exceptions are unpublished. Sierra has ruled out seats, not fixed fees. Export is undocumented too.

Decagon and Ada sell the same enterprise agent through the same sales-gated motion. Intercom publishes $0.99 per resolution and decides itself what counts, which is worse on incentives and better on comparability: you can price it before the call. All three file under AI support agents.