The per-minute rate is the smallest number.
Usage pricing covers the model and telephony cost of a live call, but says nothing about the engineering that decides what the agent should do, how it escalates, and what it writes back to your systems. That work is usually quoted separately.
Integration work is where the real cost sits.
An agent that only talks is a novelty. One that checks availability, books an appointment, and updates a CRM record needs integration work scoped against your specific tools, not a generic template.
Testing costs more than building.
A reliable agent needs testing against ambiguous requests, interruptions, and edge cases before it goes live, not just a happy-path demo. Budget time for this, because it's where most of the quality difference between agencies shows up.
Ongoing tuning is a real line item.
Real conversations surface gaps a first version missed. A fair proposal includes a defined period of post-launch tuning, not just a handover and a support email address that goes quiet.
What a reasonable first engagement looks like.
A focused agent for one job, inbound qualification or after-hours booking, with clear success measures and a scoped integration, is a more honest starting point than a broad promise to handle all your calls.
Bring your workflow, your constraints, and the outcome you want to achieve.