An AI that answers your phone.
The newest AI voice models sound human, reason in real time, and plug into an actual phone line. That means a receptionist that works 24/7, never misses a call, and costs cents per conversation. Here is how it is put together — and the honest parts.
- 01
Pick the voice model
OpenAI's Realtime API (gpt-realtime) is the current best. It listens, reasons at GPT-5 level, and speaks back in under a third of a second, so conversations feel natural instead of stilted.
- 02
Connect a real phone number
The Realtime API supports SIP, which is what plugs an app into the actual phone network. Route your business number (via a provider like Twilio) to the agent, and it can pick up live calls, not just chat in an app.
- 03
Give it tools and a script
This is where it becomes useful. You define functions it can call — book_appointment, check_availability, take_message, transfer_to_human — and a short brief on your business: hours, services, pricing, tone.
- 04
Set the handoff rules
Decide what it handles and when it passes to a person. A good setup answers the routine 60–80% (hours, booking, FAQs) and warm-transfers anything it is unsure about, so nothing falls through.
What it handles
Cents a call, not thousands a month
You pay the voice model per minute of conversation — usually a few cents a call on the lower-cost models. Independent estimates put a full inbound volume at a few hundred dollars a month, against roughly four thousand for a human agent doing the same routine calls. The wins show up fastest on high-volume, repetitive inbound: booking, hours, order status, qualification.
The honest caveats
This is a build, not an app you download. It takes wiring the voice model to a phone provider, defining the tools, and testing the handoffs — a developer job, not a weekend one. The model also isn't free to run: you pay per call. And like any agent it can misread a messy call, so keep a human path for anything high-stakes. Done right, on the right call volume, it pays for itself fast.
Want one built for your business?
Klevere designs and builds custom AI voice agents wired into your phone line, calendar and tools — end to end.
Capabilities and pricing of the underlying voice models change quickly; check the provider’s current docs before building. Always disclose to callers that they are speaking with an automated assistant where your local rules require it.