curl --request POST \
  --url https://api.dev.kathan.tech/calls \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "phone_number_id": "<string>",
  "to_number": "<string>",
  "assistant_id": "<string>",
  "label": "<string>"
}
'

{
  "id": "<string>",
  "to_number": "<string>",
  "provider": "<string>",
  "status": "<string>",
  "phone_number_id": "<string>",
  "assistant_id": "<string>",
  "from_number": "<string>",
  "provider_call_sid": "<string>",
  "direction": "<string>",
  "created_at": "<string>",
  "duration_seconds": 123,
  "timestamp": "<string>",
  "summary": "<string>",
  "greeting_one_liner": "<string>",
  "user_messages": 123,
  "agent_messages": 123
}