curl --request POST \
  --url https://api.staging.kathan.tech/campaign \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-User-ID: <api-key>' \
  --data '
{
  "name": "<string>",
  "assistant_id": "<string>",
  "phone_number_id": "<string>",
  "channel": "twilio",
  "schedule_start_time": "<string>",
  "schedule_end_time": "<string>",
  "max_concurrency": 5,
  "retry_policy": {},
  "speech_settings": {
    "style": "neutral",
    "responsiveness": "balanced",
    "interruptions": "on",
    "emotions": "natural"
  },
  "campaign_context": "<string>",
  "opening_message_template": "<string>",
  "use_returning_greeting": false,
  "use_short_term_summaries": false,
  "short_term_summaries_limit": 123,
  "recipients": [
    {
      "phone_number": "<string>",
      "metadata": {},
      "assistant_overrides": {}
    }
  ]
}
'

{
  "id": "<string>",
  "name": "<string>",
  "assistant_id": "<string>",
  "channel": "<string>",
  "phone_number_id": "<string>",
  "status": "<string>",
  "max_concurrency": 123,
  "retry_policy": {},
  "speech_settings": {
    "style": "neutral",
    "responsiveness": "balanced",
    "interruptions": "on",
    "emotions": "natural"
  },
  "caller_id_number": "<string>",
  "schedule_start_time": "<string>",
  "schedule_end_time": "<string>",
  "campaign_context": "<string>",
  "opening_message_template": "<string>",
  "use_returning_greeting": false,
  "use_short_term_summaries": false,
  "short_term_summaries_limit": 123,
  "created_at": "<string>",
  "updated_at": "<string>"
}