telnyx-voice-agent

Telnyx Phone Voice Agent

A phone/PSTN voice agent that uses a browser-side Telnyx WebRTC bridge to route a live phone call through a Cloudflare Agent.

Flow: phone call → Telnyx WebRTC bridge in the browser → Cloudflare Agent → Telnyx STT → Workers AI → Telnyx TTS → audio injected back into the phone call.

Prerequisites

1. A Telnyx account
2. A Telnyx API key
3. A Telnyx SIP Credential Connection
4. A Telnyx phone number assigned to that SIP connection

Setup

npm install
cp examples/telnyx-voice-agent/.env.example examples/telnyx-voice-agent/.env

Edit .env and set:

TELNYX_API_KEY=...
TELNYX_CREDENTIAL_CONNECTION_ID=...

For deployed Workers, store both values as secrets:

cd examples/telnyx-voice-agent
wrangler secret put TELNYX_API_KEY
wrangler secret put TELNYX_CREDENTIAL_CONNECTION_ID

Run locally

npm run start -w @cloudflare/agents-telnyx-voice-agent

Open the local URL and click Connect phone bridge. The browser fetches a short-lived Telnyx WebRTC token, opens a WebSocket to the Cloudflare Agent, then waits for an inbound phone call. Call the phone number assigned to your Telnyx SIP connection; inbound calls are auto-answered and routed through the AI agent.

The browser acts as a control panel and bridge. Audio comes from the phone call and returns to the phone call — it does not use the browser microphone or speakers. Keep the browser tab open for the duration of the call; closing it closes the live WebRTC bridge.

Deploy

npm run deploy -w @cloudflare/agents-telnyx-voice-agent

This example intentionally allows unauthenticated token creation for local demos. Before deploying publicly, replace allowUnauthenticated: true with an authorize() callback so arbitrary visitors cannot mint Telnyx credentials on your account.

Key pattern

The Worker exposes a JWT endpoint that creates browser Telnyx credentials without exposing the API key:

if (url.pathname === "/api/telnyx-token") {
  const endpoint = new TelnyxJWTEndpoint({
    apiKey: env.TELNYX_API_KEY,
    credentialConnectionId: env.TELNYX_CREDENTIAL_CONNECTION_ID,
    allowUnauthenticated: true // local demo only
  });
  return endpoint.handleRequest(request);
}

The browser creates the Telnyx bridge and gives it to TelnyxPhoneClient:

const telnyx = await createTelnyxVoiceConfig({
  jwtEndpoint: "/api/telnyx-token",
  autoAnswer: true
});

const phoneClient = new TelnyxPhoneClient({
  transport: new WebSocketVoiceTransport({ agent: "my-voice-agent" }),
  bridge: telnyx.bridge
});

phoneClient.connect();

For production, replace allowUnauthenticated: true with an authorize() callback before exposing browser-created Telnyx credentials.

Related examples

• examples/voice-agent — browser microphone/speaker voice agent
• examples/voice-input — reusable voice input component