News and insights from the ThunderPhone team.

Today we're launching TranslateMyCall: a free phone number that works as a live interpreter.

Call (228) 888-8666 from any phone — landline or mobile, no app, no account — and an AI interpreter joins the line. Then use it one of two ways:

• On a phone call. Merge in the person you're calling with your phone's merge-calls button. You speak English, they hear Spanish (or Mandarin, or Arabic, or Ukrainian…), and their reply comes back to you in English. Both directions, out loud, in real time.
• Face to face. Put the phone on speakerphone between you and someone who doesn't share a language with you. Each of you just talks.

47 languages are fully supported, and another two dozen usually work with reduced quality. Try yours.

Why we built it

Over-the-phone interpreting is one of those quietly enormous industries: hospitals, courts, insurers, and call centers spend billions a year connecting human interpreters to phone calls, usually with a few minutes of setup per call. Meanwhile, everyone else — the person calling a landlord, a clinic, a parent-in-law — simply goes without.

We build ThunderPhone, a voice-AI platform whose whole job is handling real phone calls well: noisy audio, interruptions, accents, and 47 languages. A live interpreter is what that engine looks like with the volume turned up, so we packaged it into the simplest possible product: one number anyone can dial.

Simple by default

There's no account to create, no app to install, and nothing to configure — any phone you can dial from is enough. Calls may be recorded while we tune the service, and your conversations aren't sold or used to build profiles.

Free for a limited time

TranslateMyCall is free right now — standard carrier charges aside, the interpreting itself costs nothing. Call the number, put it through its paces, and tell us what worked and what didn't.

For language service providers

The same engine is available as ThunderPhone Interpreting: a fully white-label over-the-phone interpreting platform for LSPs, with dedicated numbers per language pair, dashboards and call logs, and compliance and data-residency options — your brand, our engine. If you run an interpreting book of business and want to see what AI interpreting does to your unit economics, email sales@thunderphone.com or visit our enterprise page.

And if you want the engine itself — AI phone agents for your own call workflows, from 2¢/minute — that's ThunderPhone.

(228) 888-8666. Pick up the phone. Be understood.

Today, I’m excited to announce the public launch of our ThunderPhone v2 self-serve platform.

Anyone can now use ThunderPhone off the shelf to automate a wide variety of phone calls.

How we got here

Since last year, we’ve been working with a small group of enterprise customers to automate their phone calls. In some cases, these calls have been in performance-sensitive use cases, like pre-sales and data entry, where we found that existing AI voice platforms made so many mistakes that too many callers would get frustrated and hang up, ruining the unit economics of the use case.

To solve those problems, we ended up building a custom stack from scratch to make fewer mistakes on calls and make difficult use cases possible. After automating thousands of production calls this year, we’re now making our stack available to the public as the ThunderPhone v2 self-serve platform.

Three tiers, starting at 2c/min

Our system starts at just 2c/min for the Spark tier, models included, making it the lowest-priced full-stack voice AI platform on the market. For more speed, we also offer Bolt from 5c/min. For the highest possible intelligence, we offer Storm from 9c/min.

Storm can handle even the most complex call flows with high reliability, with no need for hand-built “flow builder” setups - one prompt is enough.

With its extra-intelligence option enabled (+3c/min), Storm scores 99.4% on Big Bench Audio, ahead of every model on the Artificial Analysis leaderboard to date. Our eval set and transcripts are public on Hugging Face, and we'll be sharing more benchmark results soon. If you want to minimize mistakes on your production calls, Storm is your best bet.

The integrated architecture

ThunderPhone can be both smarter and cheaper than other stacks because of our unique integrated architecture. Instead of a “3-step pipeline” combining one transcription model, one LLM, and one text-to-speech model, we run a more complex “web of models” where multiple transcription models, multiple LLMs, etc. all interact in carefully orchestrated ways to achieve the best possible performance at the lowest possible cost.

Among other benefits, this makes our agents exceptional at hearing callers correctly, even in noisy environments or through heavy accents. This leads calls to go more smoothly, with more reliable data entry for names, addresses, and more. ThunderPhone agents typically get even tricky spellings right in a single conversation turn, while other systems often need several tries. And every "sorry, could you spell that one more time?" is another frustrating experience for the caller that may lead them to hang up.

Our system also includes numerous components that handle the hard parts of real-life calls, including background noise, poor audio quality, interruptions, and more. We’ve tuned the conversation-handling functionality on thousands of hours of real-world data, and it provides a significant boost to the experience of real callers.

A complete platform

ThunderPhone also features a comprehensive platform that makes it exceptionally easy to build, test, deploy, and monitor voice agents. Without ever leaving ThunderPhone, you can:

• Configure voice agents for inbound and outbound calls
• Manage phone numbers and SIP trunks
• Test voice agents on real calls with AI or manual testing
• Monitor calls live as they happen, and steer them if desired
• See automatically identified problems in your production calls, and review and apply automatically-proposed fixes
• See how your calls are performing and where they need work, including step-by-step funnel metrics.

The ThunderPhone platform also makes it effortless to wire up telephony and software integrations. A setup wizard connects your existing Twilio or Telnyx account, or any standard SIP trunk, with a few details from your provider, and native connectors cover Google Sheets, Google Calendar, HubSpot, Salesforce, and Cal.com. And for all other integrations, a wizard allows for “just paste-and-click” connections to any API.

An always-on copilot is integrated into the web app to make it trivially easy to figure out how to use the ThunderPhone platform. It can even navigate the app and take actions for you - and since we’re a voice AI company, it can of course talk to you instead of making you type.

APIs, enterprise, and compliance

For use cases requiring more customization than the web platform offers, ThunderPhone also has a full-featured API to make a variety of custom integrations possible. And for even deeper platform customization, custom cost and latency requirements, compliance needs, etc., we offer bespoke enterprise implementations and support. (Contact me directly with inquiries - alex@thunderphone.com)

ThunderPhone is HIPAA and GDPR compliant for healthcare and EU/UK applications out of the box, and we sign BAAs and DPAs at no extra charge.

Try it today

For more information, have a look around our website, which goes deeper into our technology, pricing, platform features, and more.

Better yet, give ThunderPhone a try and see how it does for your use case. It should take you just a few minutes to get started.

If you run into any issues or have any requests, reach out to me personally at alex@thunderphone.com

Alex Kolchinski, CEO

Today, we’re proud to announce the public launch of ThunderPhone, which makes it easy to automate phone calls with AI. With a completely different integrated architecture from other phone AI platforms, ThunderPhone is able to achieve much higher performance, lower cost, and fewer integrations headaches. ThunderPhone supports inbound and outbound calls in dozens of languages and is HIPAA and GDPR compliant.

The Integrated Advantage

Other phone AI platforms limit the performance of their systems by enforcing a 3-step structure to their systems:

1. One transcription model, which turns the user’s voice into text.
2. One LLM, which processes the user’s text and outputs a response.
3. One TTS model, which turns the response text back into audio.

Most of them also push engineering work onto their users by forcing users to pick which models they want to use, as well as configuration options like denoising and responsiveness parameters.

We’ve taken a different approach: we’ve configured what is in our opinion the best possible stack with the models of today, and made it ready to use without complex configuration effort. Our system uses many models at the same time, with the system routing between them intelligently depending on the flow of the conversation. This includes:

• Combining multiple transcription models, some faster than others, some more accurate than others, to balance speed with accuracy and cover for each others’ mistakes.
• Combining audio-input LLMs, which can have lower general intelligence but better audio understanding, with text-only LLMs, which can make mistakes from inaccurate transcripts but are often smarter.
• Combining fast but stupid LLMs, which can generate quick responses, with much smarter but slower LLMs, which can run in the background and make sure the AI is following its prompt and responding to what the user says correctly.
• Combining commercial models from top providers including OpenAI and Google, which offer the highest intelligence available today, with a wide assortment of open-source models, which often offer better speed at lower cost.
• Using multiple models simultaneously to classify and eliminate background noise, side conversations, and other distracting noise which can otherwise derail a conversation.

These components and more are orchestrated in different ways in our three service tiers, Spark, Bolt, and Storm — optimizing Spark for cost, Bolt for speed, and Storm for intelligence, while minimizing the drawbacks of each as much as possible. All three systems share benefits like incredibly accurate understanding of what users say, even with proper nouns and spelling.

We find that this tightly-integrated architecture gives our system far higher performance at lower cost than the rigid 3-step approach offered by other vendors. In line with Clay Christensen’s modularity theory, it’s still early days in voice AI, and it’s still more valuable to maximize performance with an integrated architecture than it is to maximize customizability with a modular architecture.

Optimized Decisions

And as far as customizability goes, we are against it! Most of today’s phone AI platforms force users to navigate endless choices, from the exact models used, to ultra-detailed parameters like how quick the AI is to interrupt the user.

In our opinion, it is OUR job to optimize these choices behind the scenes so that ThunderPhone’s users can focus on what they are good at and not worry about detailed voice AI configuration. We see ourselves as a sort of Squarespace, making it easy for our users to set up phone agents at the absolute highest performance possible with today’s models, without lifting a finger.

Ease of Use

ThunderPhone is also incredibly easy to use, whether you’re setting up a new phone agent, or migrating from a different platform or from a custom stack. All that it’s necessary to do to set up a phone agent on ThunderPhone is:

1. Decide whether you want to use Spark, Bolt, or Storm.
2. Choose a voice.
3. Give us your prompt. No multi-prompt agents needed! If your prompt is too complicated for Spark or Bolt, upgrade to Storm, which can handle even complex use cases with a single prompt.
4. Connect software integrations (any endpoint, or native n8n integration) with an incredibly easy-to-use wizard.
5. Connect your VoIP with an incredibly easy-to-use wizard.

All of this typically takes 10 minutes or less.

ThunderPhone is HIPAA and GDPR compliant, and we will sign and provide BAAs and DPAs upon request.

Our Story

We’re a team of Stanford AI Lab and Y Combinator alumni that have been working on voice AI since 2024. Originally, our focus was on Flux Interpreting, which translates phone calls between languages. But after being repeatedly asked by customers to automate phone calls for their businesses instead of just translating them, we shifted focus to what is now ThunderPhone.

The Problem with Existing Platforms

Initially, we began by building phone agents for customers on other company’s phone AI platforms. We tested just about every phone AI platform on the market, but unfortunately found them lacking, especially when it came to:

• Audio understanding: The limitations of only having one transcription model to turn the user’s audio into text meant that the AI would often “mishear” the user, especially with proper nouns, uncommon words, and spellings.
• Instruction following: Having a single fast LLM doing the actual “brainwork” behind the call meant that the AIs would often struggle to follow instructions correctly and go off the rails.
• Difficult integrations: The platforms we tried made it very hard to connect to external software, generally making us type in extensive JSON configurations for tool calls and bash against them repeatedly with little to no feedback until they suddenly started working.
• Price: Existing platforms generally charged an arm and a leg: usually 10 cents a minute or more for so-so performance.

Building Our Own Stack

When we signed a deal to implement a sales call use case for an enterprise client, we were forced to build our own custom stack to meet their needs. This use case was demanding: unlike customer support, where callers are largely at the business’s mercy, sales callers are quick to hang up.

Call quality must be top-notch to make the sale instead of losing the lead. This meant handling extensive proper nouns and spellings, including names and addresses, that are hard for standard transcription models to get right. To nail this use case, we built what is now ThunderPhone.

Along the way, we kept meeting people in the San Francisco voice AI community who were building vertical phone agent companies — for veterinarians, truck drivers, and more. Surprisingly, most of them had the same opinion: existing platforms were good enough for demos, but not for production.

Shockingly, many if not most of our friends in vertical voice AI companies were actually “rolling their own” stacks... This made no sense to us — it’s really the equivalent of web startups in the 90s having to host their own web servers on a server in their closet.

With that insight, we realized that it was time to turn our phone AI system into a platform that anyone could use.

Vertical voice AI companies and consultants should be able to focus on meeting the needs of their target market with their industry-specific expertise — not on intricately engineering the underlying AI and phone technology! That’s what we’re launching today with ThunderPhone.

It’s been a long road to get here! Apologies to everyone who’s signed up with us since last April and is still waiting for access: what we thought would be a quick sprint to finish the job turned out to be a multi-month odyssey figuring out how to weave together the models available today into a system that’s as robust as possible.

But now we’re live at last — give it a try and see what you think!

While we’ve worked out the major kinks, there are sure to still be bugs in the system. If you find any issues, please email alex@thunderphone.com and I’ll see that it gets fixed for you ASAP. Let me know if you have any feature requests as well, and we’ll make those happen for you as soon as we can as well.

And if you have more custom needs, such as custom implementation and integration support, compliance beyond regular HIPAA and GDPR, SLAs, and custom feature requests, we’re happy to talk about an enterprise deal. Reach out at alex@thunderphone.com and we’ll talk about your needs and if we can help.

And more generally: our commitment to you is that it is OUR job to make sure that ThunderPhone works out of the box with minimal effort from you, and handles your business’s calls as perfectly as it is possible to do with today’s AI, within the limits of whichever price point you choose, Spark, Bolt, or Storm. Give us a try, and we’re excited to show you what ThunderPhone can do.

Let us know what you think, and thanks for your support!