Take this into the demo

Voice Agent Platform: questions to ask

From The AI Agents Report by Iterategy · iterategy.com/research/ai-agents/jobs/voice-agent-platform/

The nine questions

Does an AI do this, or does a rule? If the answer is “when X happens it sends Y”, you are buying automation, and it should not cost AI prices.
Does it send, or does it draft? Ask for the sentence on their page that says it acts on its own.
Does it do it on its own on this plan, or on the one above? The setting that lets it act without you is often a tier up from the entry price.
What does it do with the hard cases? Ask what it holds back for you, and what happens to what it cannot resolve.
What is the cap, and what happens past it? Work out the bill at the volume you actually do, not at the included allowance.
What is the unit? Per month, per user, per location, per minute, per credit or per resolved ticket.
Who does the setup, and is it in the price?
What happens to the changes it made when I stop paying? Some tools make changes that stay only while you subscribe.
Who carries the legal side? For calling and texting customers, ask who handles consent and opt-outs.

Most of these are building blocks. Only a couple are sold as a monthly plan with minutes included; several are made for developers, and without one you may need to hire someone to set it up.
The per-minute rate on the page usually covers part of the cost. A working setup lands at roughly $0.13 to $0.30 a minute.
Cheap tiers limit how many calls it takes at once, as few as 4, so it can drop calls at a busy hour. Ask the limit on your plan.
At least one vendor keeps billing after the call passes to a person.
In reviews, slow support and the agent answering slowly lead the complaints.