import Telnyx from 'telnyx';

const client = new Telnyx({
  apiKey: 'My API Key',
});

const billingGroups = await client.billingGroups.list();

console.log(billingGroups.data);

{
  "data": [
    {
      "record_type": "billing_group",
      "id": "f5586561-8ff0-4291-a0ac-84fe544797bd",
      "organization_id": "f1486bae-f067-460c-ad43-73a92848f902",
      "name": "My billing group name",
      "created_at": "2019-10-15T10:07:15.527Z",
      "updated_at": "2019-10-15T10:07:15.527Z",
      "deleted_at": null
    }
  ],
  "meta": {
    "page_number": 2,
    "page_size": 25,
    "total_pages": 3,
    "total_results": 55
  }
}