npm install telnyx

import Telnyx from 'telnyx';

const client = new Telnyx({
  apiKey: process.env['TELNYX_API_KEY'], // This is the default and can be omitted
});

try {
  const result = await client.messages.send({ to: '+13125550001', from: '+13125550002', text: 'Hello' });
} catch (err) {
  if (err instanceof Telnyx.APIConnectionError) {
    console.error('Network error — check connectivity and retry');
  } else if (err instanceof Telnyx.RateLimitError) {
    // 429: rate limited — wait and retry with exponential backoff
    const retryAfter = err.headers?.['retry-after'] || 1;
    await new Promise(r => setTimeout(r, retryAfter * 1000));
  } else if (err instanceof Telnyx.APIError) {
    console.error(`API error ${err.status}: ${err.message}`);
    if (err.status === 422) {
      console.error('Validation error — check required fields and formats');
    }
  }
}

const response = await client.calls.actions.startForking('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

const response = await client.calls.actions.stopForking('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

const response = await client.calls.actions.startStreaming('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

const response = await client.calls.actions.stopStreaming('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

const response = await client.calls.actions.startTranscription('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

const response = await client.calls.actions.stopTranscription('v3:550e8400-e29b-41d4-a716-446655440000_gRU1OGRkYQ');

console.log(response.data);

// In your webhook handler (e.g., Express — use raw body, not parsed JSON):
app.post('/webhooks', express.raw({ type: 'application/json' }), async (req, res) => {
  try {
    const event = await client.webhooks.unwrap(req.body.toString(), {
      headers: req.headers,
    });
    // Signature valid — event is the parsed webhook payload
    console.log('Received event:', event.data.event_type);
    res.status(200).send('OK');
  } catch (err) {
    console.error('Webhook verification failed:', err.message);
    res.status(400).send('Invalid signature');
  }
});