Build vs Buy · Updated October 2026
AI Voice Agent for Small Business:Build One, Buy One, or Get One Set Up?
An AI voice agent is software that answers or makes phone calls and talks like a person: it listens, decides what to say, speaks, and can book or log the call. You can build one on a developer platform like Vapi or Retell for roughly 9–16¢ a minute in parts (plus someone’s time), buy a ready-made AI receptionist app from free to $99 a month to start, or have Lexi set up for you for $299 a month plus usage. Prices checked October 3–4, 2026.
Jump to: What it is Three routes Build cost One month, worked out Which fits you Where Lexi fits
What It Is
An AI Voice Agent Is Six Jobs Wearing One Voice.
An AI voice agent hears the caller, thinks with an AI model, speaks with a synthetic voice, picks up on a phone line, and acts through your calendar or CRM. An AI receptionist (or “AI phone agent”) is a voice agent pointed at one job: answering your business phone. The sixth job, following through after the call, is where products differ most.
It Hears
Speech-to-text turns the caller’s words into text. Accents, noise and mumbling all land here first.
It Thinks
An AI model reads what was said and decides what to say or do next. Its instructions are the prompt someone writes.
It Speaks
A text-to-speech voice says the answer out loud. This is what callers judge as “sounds human” or not.
It Picks Up
A phone number and a phone line connect it to real callers. Without one it’s a demo, not a receptionist.
It Acts
Connections to your calendar and CRM let it book, move or log a call. Without them it can only talk.
It Follows Through
What happens after the call: the text back, the follow-up, the reminder. A basic one stops when the call ends.
Three Routes
Build It, Buy It, or Have It Done for You.
Build on a platform if you have a developer and unusual needs. Buy a ready-made app if you just need calls answered cheaply. Pick a done-for-you AI teammate like Lexi if you want calls answered and leads booked and followed up without running a tech project. No rankings: the right route depends on who in your business will own it.
Route 1 · Build it
Developer platforms: Vapi, Retell
About 9–16¢ a minute in parts
You get every part, priced by the minute, and full control. Wins if you have a developer and unusual needs. Less of a fit if nobody owns the build: someone writes and tests the prompt, connects the phone line, calendar and CRM, and keeps it working.
Route 2 · Buy an app
Ready-made AI receptionists
Free to $99 a month to start
Answering and messages come built in; you add your business details. Wins on price and speed to start. The trade-off is the follow-through: booking and transfer can sit on higher plans (Rosie’s start at $149; Dialzara lists booking on its $29 plan), and the work usually stops when the call ends.
Route 3 · Get it done for you
AI teammate: Lexi
$299 a month + usage
Set up for you ($100 one-time). Answers 24/7, books, follows up with every lead, runs email and text campaigns, CRM included. Wins when you want the whole job handled, not a project. Less of a fit if you want to build your own agent or only need the cheapest answering.
From each company’s own site, checked October 4, 2026: Vapi pricing (“The platform for developers creating conversational voice AI”); Retell (“Build, deploy, and manage next-generation AI voice agents”, “Design every step of the conversation on a drag-and-drop canvas”). App prices from each app’s own pricing page, checked October 3, 2026: Smith.ai, Dialzara, Rosie, Goodcall, My AI Front Desk. Comparing apps? See the best AI receptionist for small business.
What Building Costs
A Built Voice Agent Is Billed Part by Part, Minute by Minute.
On Vapi and Retell, every minute is the sum of separate parts: the platform fee, the AI model, the voice, transcription, and the phone line. In our illustration from their own price lists, that comes to about 9–14¢ a minute on Vapi and 10–16¢ on Retell. Retell itself states a range of $0.07 to $0.31 a minute. Costs vary with the parts you pick.
| Part | Per minute | What Vapi’s page lists |
|---|---|---|
| Platform (Vapi hosting) | $0.05 | Pre-paid, $0.05/min Vapi hosting |
| Transcription (Deepgram) | $0.0095–$0.0099 | $0.0095–$0.0099/min |
| AI model (OpenAI) | $0.0077–$0.0452 | $0.0077–$0.0452/min, passed through at cost |
| Voice (ElevenLabs) | $0.0146–$0.0238 | $0.0146–$0.0238/min |
| Phone line (Twilio inbound) | $0.008 | $0.008/min, charged by the provider; Vapi’s own telephony is listed free |
| Total, per minute | $0.0898–$0.1369 | About 9–14¢ a minute, lowest to highest listed option |
| Part | Lower-cost pick | Higher-cost pick |
|---|---|---|
| Platform (Retell voice infra) | $0.055 (Retell Voice Infra) | $0.055 (Retell Voice Infra) |
| AI model | $0.0128 (GPT 4.1 mini) | $0.045 (GPT 4.1) |
| Voice | $0.015 (Retell Platform Voices) | $0.04 (ElevenLabs voices) |
| Phone line | $0.015 (Twilio / Telnyx call rate) | $0.015 (Twilio / Telnyx call rate) |
| Total, per minute | $0.0978 | $0.155 |
Not on the meter: Vapi lists $5 in free credits and packages from $0 to start, Core at $29 a month, and Pro from a $999-a-month minimum. Retell lists $10 in free credits, phone numbers at $2 a month, and SMS from $20 a month plus 1¢ a message. Vapi’s own estimate for 1,000 minutes a month is $82–$129, with its own telephony at $0. And neither meter counts the hours someone spends building and maintaining the agent.
Sources, checked October 4, 2026: Vapi pricing (“Pre-paid, $0.05/min Vapi hosting”; Deepgram transcriber $0.0095–$0.0099/min; OpenAI model $0.0077–$0.0452/min, “Models pass-through at cost”; ElevenLabs voice $0.0146–$0.0238/min; Twilio inbound $0.008/min, “Charged by provider, not Vapi”); Retell pricing (“$0.07-$0.31 / min for AI Voice Agents”; Retell Voice Infra $0.055/minute; GPT 4.1 mini $0.0128/minute, GPT 4.1 $0.045/minute; Retell Platform Voices $0.015/minute, ElevenLabs voices $0.040/minute; call rates $0.015/min; phone numbers $2.00/month; Retell SMS $20.00/month + $0.01/msg). The totals are our own illustration, not a vendor figure: two sample picks from each price list, added up. Prices change; check both pages before you build.
One Month, Worked Out
Building Is the Cheapest Meter. It’s Not the Cheapest Job.
In our own example, not a vendor figure, 100 calls a month at 3 minutes each (300 minutes) cost about $26.94–$41.07 in Vapi parts, $31.34–$48.50 on Retell, $79.00 to $225.00 on the ready-made apps below, and $344.00 on Lexi. Building wins on the bill. It loses if nobody has the time to build and look after it.
| Route | Option | Starting price | This month (300 min, 100 calls) | What you still have to do |
|---|---|---|---|---|
| Build | Vapi | Pay per minute | $26.94–$41.07 | Build, test and maintain the agent; connect calendar and CRM |
| Build | Retell | Pay per minute + $2 number | $31.34–$48.50 | Same; SMS from $20 a month plus 1¢ a message |
| Buy | Goodcall | $79/mo | $79.00 | Fits if the 100 calls come from 100 or fewer callers |
| Buy | My AI Front Desk | $99/mo | $124.00 | 100 minutes over at $0.25 |
| Buy | Dialzara | $29/mo | $144.20 | 240 minutes over at $0.48 |
| Buy | Smith.ai (AI, free plan) | Free | $225.00 | 75 calls over at $3; its Pro plan starts at $150 |
| Done for you | Lexi | $299/mo | $344.00 | Nothing to build; + $100 one-time setup. Includes follow-up, campaigns, CRM |
Read it honestly: on the bill alone, Lexi costs the most here, because she’s set up for you and keeps working after the call: booking, follow-up on every lead, campaigns and a CRM. Rosie is left out because its overage rate isn’t on the plan we checked (300 minutes is over its 250). The full cost picture: how much an AI receptionist costs.
What Building Takes
Someone Has to Own It. Here’s the Job.
Building a voice agent means writing and testing its prompt, choosing every part, connecting the phone line, calendar and CRM, watching the per-minute bill, and keeping it working after launch. With someone who has the time to own it, that’s a fair trade for full control. Without that person, it’s a second job.
Write and Test the Prompt
The instructions that decide what it says. Every odd caller you didn’t plan for is a rewrite.
Pick Every Part
Model, voice, transcriber, phone line, each priced separately. Cheaper parts and better parts are different parts.
Connect Your Calendar and CRM
Booking and logging only work once someone wires them in. Retell lists CRM and calendar integrations; someone still sets them up.
Handle the Phone Side
Numbers, call transfers and texting. On Retell, a number is $2 a month and SMS runs from $20 a month plus 1¢ a message.
Watch the Bill
Per-minute parts add up with every call. Busy months cost more, on every route.
Keep It Working
Prompts drift, tools change, callers surprise you. A built agent has an owner forever, even after launch.
From Retell’s site, checked October 4, 2026: “Add functions, integrations, call transfers, DTMF, SMS, and custom logic”; it names integrations with CRMs, calendars and telephony systems. Phone number and SMS prices from Retell pricing.
Which Route Fits You
Build or Buy: Answer One Question First.
Ask who will own the agent. If you have a developer and needs no product covers, build. If you want answering with no project, buy an app. If you want answering plus the booking and follow-up handled for you, Lexi fits. If every caller must hear a person, choose a human service instead. Still deciding whether it pays? Read is an AI receptionist worth it.
| If this sounds like you | Route that fits |
|---|---|
| “I have a developer, and our calls need something no product does.” | Build on a platform like Vapi or Retell |
| “I want a voice agent for something other than answering my phone.” | Build: a platform gives you every part |
| “I just need calls answered and messages taken, cheaply.” | Buy a ready-made app (free to $99 a month to start) |
| “Calls get answered, but leads still slip after the call.” | Lexi: booking, follow-up, campaigns and CRM in one |
| “I don’t want a tech project at all.” | Buy an app, or have Lexi set up for you |
| “Every caller must hear a real person.” | None of these: a human answering service |
The Honest Part
Where Lexi Fits, and Where She Doesn’t.
Lexi isn’t a developer platform, she isn’t the cheapest per minute, and she isn’t a human. She’s a done-for-you AI teammate for owners who want the phone answered and the leads worked without building anything. If you want to build your own agent, use a platform; if you only need answering, a cheaper app may be all you need.
Lexi Isn’t a Developer Platform
There’s no agent for you to build or program. If you want to design a custom voice agent, Vapi or Retell fits that job.
Lexi Isn’t the Cheapest Per Minute
Raw platform parts run about 9–16¢ a minute in our example. Lexi’s calls are 15¢ plus $299 a month.
Lexi Isn’t a Human
She tells callers she’s an AI. If every caller must reach a person, a human service fits better.
Lexi Works in English
She answers in English only. If your callers need another language, look elsewhere.
Lexi Doesn’t Make Up Prices
She doesn’t make up prices. A real quote needs you; she takes a message.
Where Lexi Wins
No build, no upkeep, and the work after the call: booking, follow-up on every lead, campaigns, your CRM, and a morning briefing.
What Lexi does: answers every call 24/7, says she’s an AI and that the call may be recorded, books, moves and cancels appointments, takes a message instead of guessing, follows up with every lead, writes and sends email and text campaigns, keeps your GoHighLevel CRM current, and sends you a morning briefing. Every call is recorded. She can transfer a caller to you live once transfer is set up, and for urgent calls she texts, emails, or calls you right away and flags it in your portal.
$299/month at founder pricing, locked for life, plus a one-time $100 setup fee and usage (calls $0.15/min, texts 3¢ a segment, email $0.002). Texting registration and a GoHighLevel CRM are included. The public price is $997/month. No contract, cancel any time. U.S. businesses only.
Free 6-minute demo. No card. No sales call.
Common Questions
AI Voice Agents for Small Business: Your Questions
Short answers on what an AI voice agent is, what building one costs, whether you need a developer, and how Lexi differs. Prices checked October 3–4, 2026.
An AI voice agent is software that talks with people out loud, usually on the phone: it listens, understands what they want, answers in a natural voice, and can take an action like booking an appointment. Under the hood it is several parts working together: speech-to-text that hears the caller, an AI model that decides what to say, a voice that speaks, a phone line, and connections to tools like your calendar or CRM. An AI receptionist is an AI voice agent built for one job: answering a business phone.
An AI phone agent is the same thing as an AI voice agent: an AI that answers or makes phone calls and talks with the caller in a natural voice. Vendors use the names interchangeably. What matters is what it is set up to do once it picks up, such as answer questions, book appointments, take messages, or transfer the call to a person.
Buy one if you want your phone answered and leads handled without a project; build one if you have a developer and needs a ready-made product doesn’t cover. Platforms like Vapi and Retell give you every part and charge by the minute, but someone has to design the conversation, connect the calendar and CRM, test it, and keep it working. A ready-made AI receptionist app is set up in its own product. A done-for-you AI teammate like Lexi is set up for you and also handles the follow-up after the call.
As checked on October 4, 2026, the per-minute parts on Vapi and Retell add up to roughly 9 to 16 cents a minute in our own example, before anyone’s time to build it. Vapi lists $0.05 a minute for hosting plus the AI model, voice, transcription, and phone line priced separately. Retell lists $0.055 a minute for its voice infrastructure plus the model, voice, and phone line, and gives a range of $0.07 to $0.31 a minute. Costs vary with the model and voice you pick, and the meter does not count the hours spent building and maintaining the agent.
Both charge by the minute, with the parts priced separately; as checked on October 4, 2026, Vapi’s hosting is $0.05 a minute and Retell’s voice infrastructure is $0.055 a minute, before the model, voice, and phone line. Vapi starts with $5 in free credits and lists packages from $0 to start, Core at $29 a month, and Pro from a $999-a-month minimum. Retell starts with $10 in free credits, phone numbers at $2 a month, and SMS from $20 a month plus 1¢ a message. Check both pricing pages before you build, because prices change.
Not always, but someone has to build the agent and look after it. Vapi calls itself the platform for developers creating conversational voice AI. Retell says its drag-and-drop canvas works without a developer, but someone still has to design every step of the conversation, connect your calendar and CRM, and test it. If nobody on your team wants that job, a ready-made product is the simpler route.
An AI receptionist is an AI voice agent that comes already built for one job: answering a business’s phone. A voice agent platform hands you the parts to build any kind of calling agent. A receptionist app comes with the answering, message-taking, and often booking already designed, so you fill in your business details instead of building the conversation yourself.
Yes, if it is connected to your calendar and CRM; on a build platform you set up that connection, and on a ready-made app you check which plan includes it. For example, Rosie’s $49 plan texts callers a booking link, and direct calendar booking starts on its $149 plan. Lexi checks your calendar and books, moves, or cancels appointments while the caller is on the phone, and keeps your GoHighLevel CRM current.
No. Lexi is a done-for-you AI teammate, not a platform for building your own agents. She is set up for you for a one-time $100 setup fee, answers your calls 24/7, books appointments, follows up with every lead, and runs your email and text campaigns, with a GoHighLevel CRM included. If you want to design a custom voice agent from scratch, a build platform like Vapi or Retell fits that job better.
Lexi costs $299 per month at founder pricing, locked for life, plus a one-time $100 setup fee. Usage is billed separately: calls $0.15 per minute, texts 3 cents per segment (about 160 characters), and email $0.002 per email. A GoHighLevel CRM sub-account and texting registration are included. The public price is $997 per month. No contract. Lexi is available to businesses in the United States only.
Skip the Build. Hear the Finished One.
Talk to Lexi for six minutes. Play one of your own customers and try to book an appointment, and decide for yourself.
Talk to Lexi Now →No card. No sales call. U.S. businesses only.