curl --request POST \
  --url http://localhost:8000/api/calls/outbound \
  --header 'Content-Type: application/json' \
  --header 'x-user-id: <x-user-id>' \
  --data '
{
  "agent_id": "<string>",
  "phone_number": "<string>",
  "callback_url": "<string>"
}
'

{
  "call_id": "<string>",
  "room_name": "<string>"
}