Meta Tech ProviderCompared · United States
Voice AI platforms compared, for US businesses
For a US business the choice comes down to five checks: whether you can keep your number, whether Spanish-speaking callers get an agent that answers them, how outbound calls sit with the TCPA and its calling hours, how recording works when states differ, and where WhatsApp fits when most customers phone or text. This page puts ThinnestAI beside three developer platforms on those checks, with the sources and the date we read them.
What to check
Five things to check before you choose, in United States.
Put the last column to every supplier you are weighing, ThinnestAI included.
| Check | Why it matters in United States | ThinnestAI | Ask any supplier |
|---|---|---|---|
| A number you can keep | A heating-and-cooling firm, dental office or law practice has usually printed one number on trucks, listings and invoices for years, and customers already ring it. | Connect your carrier account: for Twilio you enter the Account SID and Auth Token and we set the number up, for Telnyx one API key. We don't rent US numbers, and transfer to a person and voicemail detection don't work on an imported Twilio number. Telnyx calls the US and Canada by default. | Will the agent answer the number my customers already ring, and do I keep paying my carrier directly? |
| Spanish that callers can use | Spanish-speaking customers are common in Texas, Florida, California and the Southwest, and a dental office in Miami or a tax office in Houston loses them if the agent speaks only English. | Spanish is one of the 50 voice languages, and chat replies run in Spanish too. We claim the language, not a Mexican or other regional variety, so try the voice with Spanish speakers from your own area before you go live. | Which Spanish voices do you have, and can I hear them answer my own customers' questions? |
| Outbound consent and calling hours | The FCC ruled in February 2024 that AI-generated voices are artificial voices under the TCPA, so telemarketing calls made with one need prior express written consent. Solicitations may not be made before 8 a.m. or after 9 p.m. at the called party's location (47 CFR 64.1200, eCFR, read 25 October 2026). | You set calling hours per campaign on the called person's clock and keep your own do-not-contact list. The agent does not collect consent or check the National Do Not Call Registry. Some states set narrower hours or extra rules, so set each campaign to match. | Who collects and stores the consent, and who checks the Do Not Call Registry, before a campaign runs? |
| Recording and privacy | Some states require every party to a call to consent before it is recorded, so a business that records needs a way to say so at the start of each call. | Recording is a per-agent switch that stays off until you turn it on, and the opening line is yours to write, so it can say who is calling, why, and that the call is recorded. The privacy policy sets out how calls are processed, and we support region deployments for enterprise customers. | Is recording off by default, and can the opening line tell the caller a recording is running? |
| Texts, WhatsApp and billing | Most US customers phone and text by SMS, and Meta says WhatsApp does not currently deliver marketing template messages to US phone numbers (read 25 October 2026). | This product does not send SMS, so voice is the main channel here and WhatsApp is secondary: replies after a customer writes first still work. Billing is in US dollars by card, through a merchant of record that handles sales tax. | Do you send text messages, and how do you handle a customer who messages on WhatsApp after a missed call? |
Side by side
ThinnestAI and three developer platforms, for United States.
Cells about other companies come from their own documentation, read on 25 October 2026.
| ThinnestAI | Vapi | Retell AI | Bland AI | |
|---|---|---|---|---|
| What it is | A managed agent with a shared inbox, campaigns and a call log | A developer platform that connects speech, language-model, voice and telephony providers | A developer-first voice agent platform | Voice agents with Pathways branching flows |
| Channels | Phone, WhatsApp, website chat, Telegram: one agent, one memory | Voice-focused | Voice and chat | Voice and SMS |
| Price shape | Flat per-minute rate — see pricing | A platform fee per minute plus the providers you choose | Priced per component | Bundled per connected minute |
| Phone numbers in United States | Bring a number from your own Twilio, Telnyx or Plivo account; we don't rent US numbers | Free numbers use US area codes; outbound calls and other countries use a number imported from a carrier such as Twilio or Telnyx | Sells numbers in the US and Canada only; other countries use your own provider | Sells numbers in the US and Canada; for other countries its documentation says to contact support |
| Languages for United States | Voice in American English (British and others too) and Spanish, among 50 voice languages that include Mandarin, Vietnamese, Korean, Filipino, Portuguese and Russian; chat replies in 37 languages, Spanish included | Depends on the speech and voice providers you choose | Depends on the voice and speech providers; the dashboard greys out unsupported choices | Its site states 40+ languages; check yours on a test call |
| Agent setup | Tabbed settings, no flow canvas | Visual Workflows builder | Conversation Flow builder | Pathways branching flows |
| Shared inbox and human takeover | Yes | No | Not checked | Not checked |
| Billing | US dollars, by card | US dollars | US dollars | US dollars |
Read on 25 October 2026 from each company's own pages: Vapi (phone calling, multilingual); Retell AI (purchase a number, language); Bland AI (purchase a number, site). Products change; check each page before you decide. Prices are not compared here: ours are on the pricing page, and theirs are on theirs.
Other options
Other kinds of supplier in United States.
Kinds of supplier, not companies. Each is the right call for someone.
A live answering service
Operators answer in your business name, take messages and pass emergencies to whoever is on call. It is the better choice when every caller needs a person from the first word. It cannot answer fifty calls at once or work through a callback list.
Call answering inside trade software
Some suppliers build call answering into the scheduling or practice software made for one trade, such as home services, dental or legal. If you already run that software, the fit can be tight. A general agent suits you better when you want to choose your own calendar and keep your own number.
Building on a developer platform
A team with engineers can join speech, language-model, voice and telephony providers into exactly the agent it wants. That buys control and costs build time: your team owns the testing, the consent records and the billing for each part.
Plainly
Who should pick what.
ThinnestAI fits when
- You run a home-service, dental, medical or legal office that loses work when the phone rings out, and want after-hours calls booked into your calendar through Cal.com.
- Your callers speak English and Spanish and you want both on one number, with Spanish replies on chat as well.
- You already hold a Twilio, Telnyx or Plivo number and want an agent on it, tested from your browser before any customer hears it.
Something else fits better when
- Your plan is outbound marketing to cold lists. You need consent records and Do Not Call checks, and we provide neither; use a supplier that does and take legal advice.
- Your customers text you and you need the same assistant on SMS. This product does not send SMS.
- Callers need legal, medical or veterinary advice, or an emergency service. The agent cannot give either; put a person on the line.
Questions
Common questions.
Can I keep my US phone number?
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Do the other platforms sell US numbers?
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Does the agent check consent or the Do Not Call Registry?
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Does the agent speak Spanish?
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Test it on your own calls in United States.
Create an agent, give it your own information, and ring it from your browser before you connect a number. Then put the same test to the others.