Vendor due diligence on a voice agent is the checking you do before you sign: who owns the phone number and the recordings, what a call actually costs you, who carries the liability if a call falls outside the rules, and how you get out of the contract. It takes an afternoon. It saves you a year locked into a system that isn't yours.
The demo is not the product
Every voice agent demo is the happy path: predictable question, neutral accent, polite caller. Your operation is not that. It's the customer who talks over the agent, switches from Portuguese to English mid-sentence, calls asking for something you don't even offer, and is standing on a job site.
Ask to test off-script. Call it yourself, in real Portuguese with a real accent, and ask three things: one the agent knows, one outside its scope, and one where you change your mind halfway through. An agent that only works inside the script is an expensive phone tree — and your customer already knows how to hang up on those.
Who owns the number, the recording, and the data
This is the question that separates a vendor from a trap, and almost nobody asks it.
- The number. If the number on your ads is registered under the vendor's account, your business phone isn't yours. Cancel, lose the number. Get portability in writing.
- Recordings and transcripts. Can you export everything, in an open format, without asking nicely? That's customer history, not just audio.
- The contacts. Does the agent write into your CRM and your calendar, or does it all live in the vendor's dashboard?
If the answer to all three isn't "yours," you didn't buy customer service — you rented your own funnel.
AI voice comes with rules, and the demo won't mention them
In 2024 the FCC unanimously adopted a Declaratory Ruling recognizing that calls made with AI-generated voices are "artificial" under the Telephone Consumer Protection Act. The agent's voice isn't a cosmetic detail — it's a legal category.
And the TCPA already restricts telemarketing using artificial or prerecorded voices. Since 2012 the FCC's rules require prior express written consent before that kind of robocall, and the national Do-Not-Call registry has been in place since 2003, administered by the FTC.
In practice: answering people who call you is one thing. Dialing out with an AI voice into a list is another, and the second one is regulated. Two questions for the vendor: does the product do outbound? And does the contract say who carries the liability if a call falls outside the rules? If the salesperson can't answer, they haven't thought about it — and the caller ID showing on your customer's screen is yours, not theirs. (This isn't legal advice; recording and consent rules vary by state, and your attorney closes that part.)
Total cost, run on your own numbers
The advertised price is almost always just the subscription. The cost is something else. Add it up with your figures:
Real monthly cost = subscription + (minutes/month × overage price per minute) + telephony and numbers + (setup ÷ 12) + (your maintenance hours × what your hour is worth)
Then divide by the thing that matters:
Cost per answered call = real monthly cost ÷ calls actually answered that month
Compare that against what you already spend — and against the cost of the calls nobody answers, which is worked out in a Portuguese-speaking voice agent: what it changes in a small business's revenue.
One honest note: there is no universal multiplier. No vendor knows how your revenue will move, because no vendor knows your ticket size, your industry, or how much of your call volume is urgent versus price-shopping. Anyone leading with a fixed return figure is selling, not calculating — and that applies to us too.
Hype is expensive: what regulators have already punished
This isn't buyer paranoia. In September 2024 the FTC announced Operation AI Comply, a sweep of five enforcement actions against companies that used AI to supercharge deceptive claims. Then-Chair Lina Khan put it plainly: "there is no AI exemption from the laws on the books."
One of those cases: DoNotPay, marketed as "the world's first robot lawyer," agreed to a proposed order of $193,000 and to stop claiming it could substitute for a professional service without evidence to back it up. The practical lesson is short: ask for evidence, not adjectives. Real call logs, human-transfer rates, current customers you can actually phone.
The one-afternoon checklist
- Did I test the agent off-script, in real Portuguese?
- Is the number portable to my account, in writing?
- Can I export recordings and transcripts without asking permission?
- Does it write into my calendar and my CRM?
- What's the escalation rule to a human — is it written down?
- Does it do outbound? If so, who is responsible for consent?
- What's the overage price per minute, and what counts as a minute?
- What's my cost per answered call, using my numbers?
- Is there a minimum term, an exit fee, an automatic price increase?
- What happens to my data if I cancel tomorrow?
- Can I talk to a current customer roughly my size?
- Has anyone shown me a dashboard with real numbers, or only slides?
A vendor who answers all twelve without dodging is selling you an operation. One who pivots to "AI handles everything" is selling you a demo.
If you want to see how the architecture is actually assembled — agents, handoff rules, integrations — the Voxatra platform lays out the full design. And what you can and can't automate in customer service covers the technical limits before the commercial conversation.