Stop optimizing the cheapest minute.
A low per-minute rate can still produce an expensive outcome when few calls connect or complete the task. Model the whole funnel from attempts to successful calls.
pilot discipline
Give success one testable definition
Do not let every completed call count as success. Pick a business event that can be checked in your CRM, booking system, payment flow, or support record.
Compare the result with the same outcome from human agents, not only with the carrier or platform bill. Add transfer handling, failed-attempt charges, compliance review, and implementation cost when they are material.
Use the stack calculator to estimate the all-in minute and thetelephony calculator to isolate calling charges.