Retell AI and Vapi are toolkits for building voice agents. You choose the language model, the voice and the phone carrier, write the prompts, connect your own systems, and pay per minute for each piece. ModPhone is the finished product: an AI receptionist you set up from your website and run from a dashboard, for a monthly price.
Both approaches work. The right one depends less on the technology and more on who at your organization will build the agent, and who will fix it when your hours change or a caller finds a question it can't answer.
What Retell and Vapi cost, as of September 2026
Retell's pricing page is pay as you go: $0.07 to $0.31 a minute for voice agents, depending on the pieces you choose. The minute rate is built from parts:
| Retell component | Price |
|---|---|
| Voice infrastructure | $0.055 a minute |
| Text to speech | $0.015 a minute for most voices, $0.04 for ElevenLabs voices |
| Language model | From about $0.002 to $0.64 a minute, depending on the model |
| Phone calls through Retell's carriers | $0.015 a minute |
| Knowledge base | $0.005 a minute extra, first 10 knowledge bases free |
| Phone number | $2 a month |
New accounts get $10 in free credits and 20 concurrent calls, with more at $8 per concurrent call per month. Calls are billed to the second. Retell says it is SOC 2 certified and HIPAA-ready, and it offers an Enterprise plan with custom pricing.
Vapi's pricing page charges $0.05 a minute for hosting, plus the transcription, language model and voice providers at their own cost with no markup. Its calculator estimates 1,000 minutes a month at $82 to $129 with Deepgram, OpenAI and ElevenLabs. You get $5 in free credits, one phone number and 4 concurrent calls to start. Paid support packages start at $29 a month (Core) and $999 a month minimum (Pro), and HIPAA compliance is a $2,000-a-month add-on.
ModPhone's plans are Starter at $49 a month (200 minutes, 200 texts), Growth at $99 (500 minutes, 500 texts, website chat, webhooks) and Business at $299 (1,500 minutes, 1,000 texts, email agent). Business is the plan most customers pick. That works out to roughly $0.20 to $0.25 a minute, with the phone number, texts and everything below included.
So which is cheaper?
On minutes alone, a carefully tuned Vapi or Retell agent can cost less than ModPhone. Vapi's own estimate for 1,000 minutes is $82 to $129 a month, where ModPhone would be Growth plus extra minutes ($159) or Business ($299).
The difference is labor. With Retell or Vapi, somebody has to do the following, and then keep doing it:
- Write and test the prompts, and decide how the agent handles the calls you didn't plan for.
- Load your business knowledge and keep it current when prices, hours or staff change.
- Connect the calendar so the agent books real slots, and send the caller a confirmation.
- Set up transfers to your staff, including what happens when nobody answers.
- Give your staff somewhere to read transcripts and follow up on calls that need a person.
- Watch for problems when a model or provider changes.
Retell includes building blocks for several of these, such as call transfer, appointment booking and a knowledge base. Both platforms offer testing and simulation tools, and Retell has pre-built templates. Someone still configures, connects and maintains them. If that person is already on your payroll and likes the work, the per-minute savings are real. If it means hiring a contractor, add that cost before you compare.
What ModPhone does without the build
ModPhone reads your website and documents (PDFs, Word files, Google Drive or OneDrive folders) and turns them into facts you can review and edit one by one. It books into Google Calendar or Outlook and texts the caller a confirmation. It transfers to your staff or departments, can ring a list of people in order until someone presses 1 to accept, and can offer a callback when nobody picks up. It texts callers a link or an address mid-call. After each call your team can get an email with the summary and a link to the transcript, and calls that need a person land in a follow-up list. The same agent answers texts on every plan, website chat from Growth and email on Business, in 30+ languages.
You can try the demo in 30 seconds and be live on a real number in about 10 minutes.
Who should pick Retell or Vapi
You have engineers, and voice is part of your product or your core operations. You want to choose the language model and voice yourself, or switch them as new ones come out. You are an agency or software company building agents for many clients. You make outbound calls at volume. Or you need a published path to HIPAA compliance: Retell describes itself as HIPAA-ready, and Vapi sells a HIPAA add-on.
Who should pick ModPhone
The person who will own the agent is an office manager, not a developer. You want it answering calls this week. You want a predictable monthly bill that includes the number and texts. You want your staff to have one inbox for calls, texts, chats and email, on the web and in the iPhone and iPad app.
Common questions
Is Retell or Vapi cheaper than ModPhone?
Per minute, often yes. As of September 2026, Retell runs $0.07 to $0.31 a minute depending on the model and voice, and Vapi estimates $82 to $129 for 1,000 minutes, compared with roughly $0.20 to $0.25 a minute on ModPhone. Those rates don't include the time to build, connect and maintain the agent, which ModPhone's price covers.
Can I use Retell or Vapi without a developer?
You can build a simple agent in either dashboard, and Retell offers pre-built templates. Connecting a calendar, a CRM or transfer rules, and keeping the agent working as things change, usually needs someone comfortable with prompts, APIs and webhooks.
Can I choose the AI model in ModPhone?
No. ModPhone manages the model for you, so there is nothing to pick or update. You control what the agent knows and how it behaves through your knowledge base, instructions and settings. If choosing the model matters to you, Retell or Vapi is the better fit.
Does ModPhone have an API?
ModPhone sends call and chat results to your own systems by webhook, which is how it connects to Zapier, Make, n8n or your own software (Growth plan and up). It isn't a platform for building your own voice applications.
Compare it with your own build
If you have a prototype on Retell or Vapi, give the ModPhone demo the same website and the same test questions.