curl --request POST \
  --url https://inbound.new/api/e2/onboarding/demo \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "apiKey": "<string>",
  "to": "<string>"
}
'

{
  "id": "<string>",
  "messageId": "<string>"
}