{
  "sender_id": "MYBIZ",
  "reason": "Business messaging"
}

{
  "success": true,
  "message": "Sender ID request submitted",
  "sender_id": {
    "id": "550e8400-e29b-41d4-a716-446655440000",
    "sender_id": "MYBIZ",
    "status": "pending",
    "created_at": "2025-11-27T10:30:00Z"
  }
}