Quickstart

curl -X POST "https://api.x.com/2/calls" \
  -H "Authorization: Bearer $USER_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"title": "Support line", "join_policy": "open"}'

{
  "data": {
    "id": "t69-8sb-6z5",
    "title": "Support line",
    "join_policy": "open",
    "host_id": "2099230323825426442",
    "participant_count": 0,
    "created_at": "2026-09-24T02:10:00.000Z",
    "join_url": "https://call.x.com/t69-8sb-6z5",
    "viewer_may_join": true
  }
}

curl -X POST "https://api.x.com/2/calls/t69-8sb-6z5/join" \
  -H "Authorization: Bearer $USER_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"media": {"type": "websocket", "audio": {"encoding": "pcm16", "sample_rate": 16000}}}'

{
  "data": {
    "session_id": "cs_4f1c2a9e0b7d3a51",
    "media_type": "websocket",
    "media_url": "wss://api.x.com/2/calls/media",
    "media_token": "eyJhbGciOiJIUzI1NiJ9…",
    "expires_at": "2026-09-24T02:12:00.000Z",
    "admission": "immediate",
    "call": { "id": "t69-8sb-6z5", "join_policy": "open" }
  }
}

const ws = new WebSocket(`${session.media_url}?token=${encodeURIComponent(session.media_token)}`);
ws.binaryType = "arraybuffer";
const send = (command) => ws.send(JSON.stringify(command));

ws.onmessage = ({ data }) => {
  if (data instanceof ArrayBuffer) {
    // 20 ms of everyone else in the call: feed it to your model.
    return;
  }
  const event = JSON.parse(data);
  switch (event.type) {
    case "session.joined":
      // Your agent is in the call. Send its voice as binary frames of any size.
      break;
    case "speech.started":
      send({ type: "audio.clear" }); // someone started talking: stop your agent
      break;
    case "session.ended":
      ws.close();
      break;
  }
};