The build is the smaller number
Most quotes for a voice agent price the integration work and stop there. That is the one-time cost, and it is usually not the number that decides whether the project survives its first year.
The recurring cost is per-minute: speech-to-text, the model, text-to-speech, and telephony. It scales directly with how much your phone actually rings, which means the business case depends on call volume you can measure today.
What to measure before you commit
Before scoping an agent, get these four numbers. They decide the design more than any feature list does.
- Calls per day, and the peak hour rather than the average.
- Average call length in minutes.
- What share of calls are the same three questions — that share is what an agent can actually absorb.
- What a missed call costs you. Without this, no automation can be justified honestly.
Where agents earn their keep, and where they do not
An agent is worth it when a large share of calls are repetitive, the caller wants a fast answer more than a person, and missing the call has a real cost. Booking, availability, opening hours, order status.
It is a poor fit when calls are unpredictable, emotionally loaded, or high-value enough that a human should always answer. We will say so during scoping rather than after.