speechmatics · J-Jaywalker · Jul 28, 2026
diff --git a/docs/integrations-and-sdks/index.mdx b/docs/integrations-and-sdks/index.mdx
@@ -44,7 +44,18 @@ Choose an integration to build accurate, low-latency voice agents rapidly with t
 
 </Grid>
 
+## Telephony integrations
 
+Bridge phone calls into Speechmatics for real-time transcription.
+
+<Grid columns="3" gap="3">
+  <LinkCard
+    title="Twilio"
+    description="Forkable reference proxy that streams both sides of a Twilio Voice call to Speechmatics Realtime. Per-speaker transcripts to your console. Best for: engineers integrating telephony."
+    icon={<img src="/img/integration-logos/twilio.png" alt="Twilio logo" width="28px" height="28px" />}
+    href="/integrations-and-sdks/twilio"
+  />
+</Grid>
 
 ## SDKs
 

diff --git a/docs/integrations-and-sdks/sidebar.ts b/docs/integrations-and-sdks/sidebar.ts
@@ -19,6 +19,11 @@ export default {
       id: "integrations-and-sdks/vapi",
       label: "Vapi",
     },
+    {
+      type: "doc",
+      id: "integrations-and-sdks/twilio",
+      label: "Twilio",
+    },
     {
       type: "doc",
       id: "integrations-and-sdks/sdks",

diff --git a/docs/integrations-and-sdks/twilio.mdx b/docs/integrations-and-sdks/twilio.mdx
@@ -0,0 +1,189 @@
+---
+title: Twilio integration
+description: Learn how to transcribe live Twilio Voice calls with Speechmatics Realtime using a small, forkable proxy server.
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+# Twilio integration
+
+:::info
+This is a **reference implementation** — you clone it, run it, and adapt it. It's not a hosted service or a Twilio Marketplace add-on.
+:::
+
+[Twilio](https://www.twilio.com) lets you make and receive phone calls from your code. Its [Media Streams](https://www.twilio.com/docs/voice/media-streams) feature sends a live copy of any call's audio to a URL you control — perfect for real-time transcription, without touching the call itself.
+
+This guide walks you through a small proxy that takes that audio stream and feeds it into Speechmatics Realtime, printing per-speaker transcripts to your console as the call unfolds. The [reference repo](https://github.com/speechmatics/speechmatics-twilio-integration) ships the same proxy in two languages — [Python](https://github.com/speechmatics/speechmatics-twilio-integration/tree/main/python) and [Node.js](https://github.com/speechmatics/speechmatics-twilio-integration/tree/main/js) — so pick whichever fits your team.
+
+## How it works
+
+Here's what runs where before we get to the commands:
+
+```mermaid
+flowchart LR
+    A["📞 Caller A"] <-->|voice| T["Twilio"]
+    T <-->|voice| B["📞 Caller B"]
+    T -.->|copy of audio<br/>μ-law 8 kHz| P["Proxy<br/>proxy.py / proxy.ts"]
+    P -->|Realtime WebSocket| S["Speechmatics<br/>Realtime API"]
+    S -->|per-speaker transcripts| C["Your console"]
+```
+
+- **Caller A** dials your Twilio number which forwards to **Caller B** — the two talk like a direct call.
+- Twilio sends a **live copy of the audio** to your proxy over a WebSocket.
+- The proxy hands that audio to Speechmatics  with [channel diarization](/speech-to-text/features/diarization) turned on. 
+- Each speaker (`inbound` from Caller A, `outbound` from Caller B) gets its own transcript stream.
+- Speechmatics returns transcripts, and the proxy prints them under per-channel labels.
+
+Everything runs on your machine. [ngrok](https://ngrok.com) gives Twilio a public URL to reach you.
+
+## Before you begin
+
+Tick these off as you gather them:
+
+<ul style={{ listStyle: 'none', paddingLeft: 0 }}>
+  <li style={{ display: 'flex', alignItems: 'baseline', gap: '0.6em', marginBottom: '0.4em' }}>
+    <input type="checkbox" />
+    <span>A Speechmatics API key from the <a href="https://portal.speechmatics.com">Speechmatics portal</a>.</span>
+  </li>
+  <li style={{ display: 'flex', alignItems: 'baseline', gap: '0.6em', marginBottom: '0.4em' }}>
+    <input type="checkbox" />
+    <span>A <a href="https://www.twilio.com">Twilio account</a>, a voice-capable Twilio phone number, your Account SID, and your Auth Token.</span>
+  </li>
+  <li style={{ display: 'flex', alignItems: 'baseline', gap: '0.6em', marginBottom: '0.4em' }}>
+    <input type="checkbox" />
+    <span>A <strong>second</strong> phone number you own or have verified with Twilio to call.</span>
+  </li>
+  <li style={{ display: 'flex', alignItems: 'baseline', gap: '0.6em', marginBottom: '0.4em' }}>
+    <input type="checkbox" />
+    <span>An <a href="https://ngrok.com">ngrok</a> account and auth token.</span>
+  </li>
+  <li style={{ display: 'flex', alignItems: 'baseline', gap: '0.6em', marginBottom: '0.4em' }}>
+    <input type="checkbox" />
+    <span>Python 3.9+ or Node.js 20+, depending on which implementation you pick.</span>
+  </li>
+</ul>
+
+## Clone the reference repo
+
+Both implementations live in one repo. Clone it and change into the folder:
+
+```bash
+git clone https://github.com/speechmatics/speechmatics-twilio-integration.git
+cd speechmatics-twilio-integration
+```
+
+Inside, you'll find a [`python/`](https://github.com/speechmatics/speechmatics-twilio-integration/tree/main/python) folder and a [`js/`](https://github.com/speechmatics/speechmatics-twilio-integration/tree/main/js) folder alongside a shared [`.env.example`](https://github.com/speechmatics/speechmatics-twilio-integration/blob/main/.env.example) at the root. Both implementations read from the same `.env`, so you set your credentials once and can flip between languages freely.
+
+## Set your credentials
+
+Copy the template:
+
+```bash
+cp .env.example .env
+```
+
+Open `.env` in your editor and the environment variables. The proxy won't run if any are missing.
+
+| Variable | What to put here |
+|---|---|
+| `SPEECHMATICS_API_KEY` | Your Speechmatics Realtime API key. |
+| `NGROK_AUTHTOKEN` | Your ngrok auth token from the ngrok dashboard. |
+| `TWILIO_ACCOUNT_SID` | Your Twilio Account SID — it starts with `AC`. |
+| `TWILIO_AUTH_TOKEN` | Your Twilio Auth Token. |
+| `TWILIO_PHONE_NUMBER` | Your Twilio number in E.164 form, e.g. `+442475429721`. |
+| `FORWARD_TO_NUMBER` | The E.164 number the call bridges to — the second speaker. |
+
+## Install and run
+
+<Tabs groupId="language">
+<TabItem value="python" label="Python">
+
+Move into `python/` and set up a virtualenv:
+
+```bash
+cd python
+python -m venv .venv
+source .venv/bin/activate
+pip install -r requirements.txt
+```
+
+Start the proxy:
+
+```bash
+python proxy.py
+```
+
+</TabItem>
+<TabItem value="javascript" label="Node.js">
+
+Move into `js/` and install dependencies:
+
+```bash
+cd js
+npm install
+```
+
+Start the proxy:
+
+```bash
+npm start
+```
+
+</TabItem>
+</Tabs>
+
+You'll see a banner like this:
+
+```
+Listening on ws://localhost:5000/twilio
+Twilio number +XX... pointed at wss://abc123.../twilio. Call it now.
+```
+
+## Make your first call
+
+With the proxy running, dial your Twilio number from any phone.
+
+1. Twilio answers the incoming call, plays the short greeting, then dials `FORWARD_TO_NUMBER`.
+2. Answer the second phone. You're now on a normal two-way call.
+3. Speak into either handset. Transcripts appear in the console within seconds:
+
+```
+[twilio] incoming Media Streams connection
+[twilio] call started - stream=MZxxx... call=CAxxx... tracks=['inbound', 'outbound']
+[inbound ] Hello there. How are you doing today?
+[outbound] I'm doing pretty well thanks.
+[twilio] call stopped (stream=MZxxx...)
+```
+
+- **inbound** — whoever dialed your Twilio number.
+- **outbound** — whoever answered `FORWARD_TO_NUMBER`.
+
+When you're done, press `Ctrl-C` in the terminal to stop the proxy. Your Twilio number's Voice URL stays pointed at the last ngrok tunnel — the next run overwrites it, so you never have to touch the Twilio Console after the first time.
+
+## What the proxy does under the hood
+
+Once a call arrives, the proxy has three jobs:
+
+1. **Receive Twilio's audio.** Twilio sends 20 ms of mulaw-encoded 8 kHz mono audio at a time — 160 bytes per frame. Each frame arrives on the WebSocket as a JSON `media` event with a base64 `payload` and a `track` label (`inbound` or `outbound`). The proxy uses that label to keep the two speakers apart.
+2. **Forward the audio to Speechmatics as-is.** Speechmatics Realtime accepts mulaw 8 kHz directly, so the proxy passes bytes straight through without re-encoding. That keeps latency down and avoids audio-quality loss.
+3. **Ask Speechmatics for per-channel transcripts.** The session is configured with `diarization: "channel"` and channel labels `["inbound", "outbound"]`. Every transcript that comes back carries a `channel` field, and the proxy prints it under the matching label.
+
+## Troubleshooting
+
+| Problem | What to try |
+|---|---|
+| **`Missing required env vars in .env: ...`** | Copy `.env.example` to `.env` at the repo root and fill in every listed value. Both languages read the same file. |
+| **`Twilio number ... not found on this account`** | Check `TWILIO_PHONE_NUMBER` is in E.164 form (leading `+`, country code, no spaces) and belongs to the account whose SID and token you're using. |
+| **Twilio Debugger shows `21219 - 'To' phone number not verified`** | Your Twilio account is in trial mode. Add `FORWARD_TO_NUMBER` at [Verified Caller IDs](https://console.twilio.com/us1/develop/phone-numbers/manage/verified), or upgrade the account. |
+| **The caller hears "an application error has occurred"** | Open the [Twilio Debugger](https://console.twilio.com/us1/monitor/logs/debugger) for the specific error code. Confirm ngrok is still running and the URL in the startup banner matches your number's Voice URL in the Twilio Console. |
+| **No transcripts appear** | Confirm you heard the "This call is being transcribed" greeting — that proves Twilio reached `/twiml`. If not, the proxy isn't reachable. If yes but transcripts still don't come through, double-check `SPEECHMATICS_API_KEY`. |
+
+Still stuck? See [Twilio support](https://support.twilio.com) or [contact Speechmatics](https://www.speechmatics.com/company/contact).
+
+## Next steps
+
+- [Learn about channel diarization](/speech-to-text/features/diarization)
+- [Explore all supported languages](/speech-to-text/languages)
+- [Read the Realtime API reference](/speech-to-text/realtime/quickstart)
+- [Browse more integrations in the Speechmatics Academy](https://github.com/speechmatics/speechmatics-academy)