curl --request POST \
  --url https://api.callaro.ai/api/v1/agents/{id}/attach_phone_number \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "phone_number_id": "<string>"
}
'

{
  "data": {},
  "message": "<string>",
  "meta": {},
  "request_id": "<string>"
}