Retell AI: What It Is, What It Costs, and How to Get Started

AI Voice · Review

Retell AI lets you build phone agents that talk like people. The price is per minute, and it is built from parts. Here is how to read it before you spend a dollar.

Retell AI is one of the tools people use to build AI phone agents. These are agents that answer calls, book appointments, and follow up with leads, all by voice.

On October 23, 2026, I went through Retell's website, its pricing page, and its billing docs. Here is what it does, what it really costs per minute, and how to start without a surprise bill.

What is Retell AI?

Retell AI is a platform for building voice agents. A voice agent is an AI that can talk on the phone. It listens to the caller, figures out what they want, and talks back in a natural voice.

People use these agents to:

• Answer the phone when no one is around.
• Book appointments right on the call.
• Call new leads back fast.
• Answer common questions, like hours and prices.
• Pass the call to a real person when it gets hard.

Retell also does chat agents, so the same brain can answer text messages or a website chat. And it connects to other tools. Its integrations list includes Go High Level and n8n, which helps if you already use either one.

How much does Retell AI cost?

Here is what the pricing page showed on October 23, 2026:

• Pay as you go: $0.07 to $0.31 per minute for voice agents. Chat starts at $0.002 per message.
• Free start: $10 in free credits and 20 free concurrent calls.
• Enterprise: custom pricing for big teams.

That range is wide on purpose. Retell does not charge one flat price. It adds up the parts you pick. A cheap voice and a small model sit near the low end. A premium voice and a big model push you up.

How the per-minute price is built

This is the part to read closely. On the pricing page, Retell breaks the cost into parts:

1. Voice Infra: Retell's own base cost. It was $0.055 per minute.
2. The voice: the text to speech that does the talking. Retell platform voices were $0.015 per minute. An ElevenLabs Flash voice was $0.040 per minute.
3. The AI model: the brain that decides what to say. One example on the page, GPT 5.6 Terra, was $0.064 per minute.
4. The phone line: the cost of the call itself. This depends on the country and the provider.

Here is a simple example using the numbers above. Voice Infra at $0.055, plus a Retell platform voice at $0.015, plus GPT 5.6 Terra at $0.064, comes to $0.134 per minute. That is before the phone line and any add-ons.

One good thing to know: the page says "No Charge for Sip Trunking/Custom Telephony." So if you bring your own phone setup, Retell does not add a phone fee on top. If you use Retell's phone lines, the cost depends on where you call.

Add-ons that raise your bill

Retell has extras you can turn on. Each one adds a little to your cost. Here are the ones listed on the pricing page:

• Knowledge base: +$0.005 per minute. This lets the agent answer from your own docs.
• Batch calls: +$0.005 per dial. For calling a list of people.
• Branded calls: +$0.10 per outbound call. Shows your business name on the caller's screen.
• Noise reduction: +$0.005 per minute.
• Safety guardrails: +$0.005 per minute.
• PII removal: +$0.01 per minute. Removes personal details from records.
• AI QA: the first 100 minutes are free, then $0.10 per minute.
• SMS: $0.01 per message.

There are also monthly costs:

• Retell phone numbers: $2.00 a month each.
• A verified number: $10 a month.
• SMS: $20 a month.
• Extra concurrent calls: $8 a month each after the first 20.
• Extra knowledge bases: $8 a month each after the first 10 free.

None of these are big alone. But turn on five of them, and your per-minute cost can climb fast. Only turn on what you need.

How Retell billing works

Retell uses prepaid credits. You buy credits, and your calls use them up. A few rules matter here:

• The billing docs say, "Credits never expire, but they are non-refundable once purchased."
• When your balance hits zero, the docs say calls, chat, and other usage stop until you buy more or auto recharge tops you up.
• Auto recharge "only buys credits when the balance is low."
• Older accounts on monthly invoices were moved to credits on September 30, 2026.

So start small. Buy a small amount of credits, test, and only add more once you know your real costs. Since credits are not refundable, do not load up a big balance on day one.

How to get started with Retell AI

Here is the simple path I would take:

1. Pick one job. For example, answering missed calls for a local business. One job is easier to get right than five.
2. Sign up and use the free credits. The $10 in free credits is enough to test.
3. Write the agent's script. Tell it who it is, what business it works for, what it can help with, and when to pass the call to a person.
4. Add your info. Hours, prices, and common questions. Keep it short and clear.
5. Test it yourself. Call it ten times. Try to confuse it. Fix what breaks.
6. Connect your tools. Link it to your calendar or CRM so it can book and log calls.
7. Go live slowly. Start with after-hours calls only. Watch the recordings for a week.

Common mistakes to avoid

• Writing a giant script. Long, messy instructions confuse the agent. Short and clear works better. Add rules one at a time as you test.
• Skipping the handoff. Every agent needs a way to pass the caller to a real person. Callers get upset when they feel stuck with a bot.
• Turning on every add-on. Each extra adds cost per minute. Start with none, then add only what fixes a real problem.
• Not listening to calls. Read the transcripts every day for the first week. That is where you find the questions you forgot to cover.
• Guessing your costs. Use the numbers from your own test calls, not the low end of the price range.

Know the rules before you make calls

This part is not optional. In the US, the FCC ruled that AI voices in robocalls count as "artificial" under the Telephone Consumer Protection Act. That means the same consent rules apply to AI calls as to other robocalls.

In plain English: answering calls is one thing. Calling people with an AI voice is another. Before you make outbound calls, make sure you have the right consent. If you are not sure, talk to a lawyer before you start.

Who is Retell AI good for?

Retell is a good fit if you:

• Want to build a voice agent and control each part, like the voice and the model.
• Are fine with pay per minute pricing.
• Have some comfort with setup and testing.
• Want to connect calls to tools like Go High Level or n8n.

Look at other options if you:

• Want one flat monthly price.
• Want an agent that is already built for your industry.
• Already use a CRM with voice AI built in.

If you are comparing tools, my Bland AI guide and my Synthflow AI guide cover other options, and my post on HighLevel Voice AI cost covers the built-in choice. Want to see how people turn voice agents into a service for local businesses? I walk through it in my free AI workshop.