curl --request POST \
  --url http://localhost:8000/api/sessions/{session_id}/transfer \
  --header 'Content-Type: application/json' \
  --data '
{
  "phone_number": "<string>"
}
'

{
  "session_id": "<string>",
  "transferred_to": "<string>",
  "status": "<string>",
  "message": "<string>"
}