Most CX-AI vendors bill per-seat (legacy CCaaS), per-minute (call-center heritage), or 'platform plus usage' (modern SaaS). Pay-per-resolved-case is the model that says: we charge only when the agent closed a case in your CRM.
It aligns the vendor's revenue with the customer's outcome. If the agent does not resolve a call, the customer does not pay for it. If it resolves a call but the customer hangs up frustrated and calls back later, that recall is not double-billed.
The hard part is defining 'resolved' honestly. A serious vendor publishes the resolution criteria, surfaces the per-case ledger in the CRM, and runs the billing through an auditable meter (Stripe Meter or equivalent) so the customer can verify every line item.
Vorel bills per resolved case, audited through Stripe Meter, with every line on the invoice mapped to a ticket closed in your CRM.