What an AI voice agent really costs, down to the minute
“What does a phone robot cost?” is the first question in every conversation. The honest answer: it depends on four line items, only one of which usually shows up in the sales pitch. Here is the whole model.
Item 1, the call minute
A call uses three technical services: speech to text, the language model that answers, and text back to speech. Depending on your choices that lands somewhere between a few cents and a few tens of cents per minute. Telephony sits on top, and in practice it's often the smallest of all. Calculate with your own volume, not an average from a blog: calls per month and average duration are both in your phone system. A clinic with nine hundred calls averaging two and a half minutes is a different story from an installer with a hundred and twenty calls of six minutes.
Item 2, the build, which is not the setup
An agent that picks up and reads out a script takes an afternoon. That's not where the work is. The work is in: which intents it must recognise, what it does when it doesn't understand, when it transfers, how the appointment reaches the right calendar with the right duration, what happens when the calendar is full, and how it sounds when the caller is annoyed. This is one-off, and it decides whether the agent is still switched on after three weeks. Don't squeeze this budget to shave the per-minute rate: save a hundred euros a month in minutes but miss two customers and you're worse off.
Item 3, steering it for the first six weeks
Budget an hour a week for someone listening back to real calls. You'll find things you couldn't have predicted: callers with a heavy accent, someone explaining their whole situation first, a question asked twenty times a week that isn't in the script. Each is a small adjustment that visibly lifts your success rate. Skip this item and you keep an agent that gets it right seventy percent of the time, which feels like failure, while two weeks of work sit between that and a good result.
Item 4, what it already costs you
The comparison isn't “agent versus nothing”, it's “agent versus what you pay today”. Put two things beside it: the hourly cost of whoever answers now including employer charges, and the value of a missed call. That second figure is painfully high in most businesses: at an average order of € 400 and a one-in-three conversion, every missed caller is over € 130 of expected revenue. Miss ten a week and you're talking about more than € 5,000 a month in lost opportunity. Against that number, the per-minute discussion is nearly a detail.
The short version
Missed calls per week × your average order value × your conversion rate = what you're leaving on the table. Above a thousand euros a month, a voice agent almost always pays back within a quarter. Below it, I'll tell you so.
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