Build a Voice Agent in TypeScript (no framework)

 PSTN / SIP trunk ─▶ ┌──────────────────┐                   ┌─────────────────────────────┐
                     │  voice gateway   │  ONE QUIC/WT      │ your Node worker (the SDK)   │
 browser (QUIC/MoQT) │  (owns the       │◀── session ──────▶│  register-and-wait          │
 on :443 ──────────▶ │  caller leg)     │  (worker dials    │  + your STT / LLM / TTS      │
                     └──────────────────┘   out to :443)    └─────────────────────────────┘
     caller audio ──▶ 8 kHz pcm16 ──▶ QUIC datagrams ──▶  for await (const pcm of call.audio())
     agent audio  ◀── back onto the call ◀── QUIC datagrams ◀── call.sendAudio(pcm)

npm install https://artifacts.clutchcall.dev/npm/tarballs/telequick-agents-0.3.0.tgz \
            @fails-components/webtransport

import { AgentConfig, serve, type Call } from "@telequick/agents";

async function handler(call: Call): Promise<void> {
  console.log(`call ${call.callId} from ${call.callerNumber} → ${call.calledNumber}`);
  for await (const pcm of call.audio()) {   // 20 ms pcm16 @ 8 kHz
    await call.sendAudio(pcm);              // echo caller audio back
  }
}

// Reads TELEQUICK_HOST / TELEQUICK_MEDIA_KEY / TELEQUICK_MEDIA_SECRET / TELEQUICK_AGENT
await serve(handler, AgentConfig.fromEnv({ agentName: "salesbot" }), {
  onReady: () => console.log("connected + registered — awaiting calls"),
  onDisconnected: (err) => console.warn("dropped, reconnecting:", err.message),
});

export TELEQUICK_HOST=engine.telequick.dev
export TELEQUICK_MEDIA_KEY=ck_...
export TELEQUICK_MEDIA_SECRET=...
export TELEQUICK_AGENT=salesbot
node --import tsx echo-agent.ts
# → "worker ready (agent=salesbot) — awaiting calls"

let connected = false;
await serve(handler, AgentConfig.fromEnv({ agentName: "salesbot" }), {
  onReady: () => { connected = true; },        // e.g. flip your /healthz to 200
  onDisconnected: () => { connected = false; },
});

import { AgentConfig, serve, type Call } from "@telequick/agents";

async function handler(call: Call): Promise<void> {
  // Greet first — most callers expect the agent to speak on answer.
  for await (const pcm of yourTTS("Hi, thanks for calling. How can I help?", call.sampleRate)) {
    await call.sendAudio(pcm);
  }
  await call.flush();

  for await (const pcm of call.audio()) {
    const text = await yourSTT(pcm, call.sampleRate);   // your streaming STT
    if (!text) continue;
    call.sendTranscript("user", text);

    // Caller started talking over the agent → stop playback immediately.
    await call.clear();                                 // barge-in

    const reply = await yourLLM(text);
    call.sendTranscript("assistant", reply);
    for await (const chunk of yourTTS(reply, call.sampleRate)) {
      await call.sendAudio(chunk);
    }
    await call.flush();
  }
}

await serve(handler, AgentConfig.fromEnv({ agentName: "salesbot" }));