curl --request GET \
  --url https://api.hubapi.com/communication-preferences/v3/definitions \
  --header 'Authorization: Bearer <token>'

{
  "subscriptionDefinitions": [
    {
      "businessUnitId": 123,
      "communicationMethod": "<string>",
      "createdAt": "2023-11-07T05:31:56Z",
      "description": "<string>",
      "id": "<string>",
      "isActive": true,
      "isDefault": true,
      "isInternal": true,
      "name": "<string>",
      "purpose": "<string>",
      "updatedAt": "2023-11-07T05:31:56Z"
    }
  ]
}