The advent of initiatives like Industry 4.0 promises increased operational efficiency through smart services and interconnected devices. To enable smart maintenance services for today's and future industrial equipment, regular status information must be transmitted from device customers to maintenance service providers over the Internet. However, simply attaching an industrial device to the Internet often leads to a security and privacy nightmare. Transparency about when and what data is being transmitted is of crucial interest to a customer. During transport, data must be protected against modifications and disclosure. A maintainer requires trust in the data's origin and integrity.In this paper, we propose ESTADO, a system that enables smart services by providing the necessary connectivity from industrial equipment to service providers for device state tracking. Our system design focuses on the migration of current devices and the security aspect. Using a non-permanent NFC based connection, connectivity is only established ad-hoc on customer demand, and any data transmission is fully transparent to a customer. We study our design through a prototype implementation using an Infineon security controller and evaluate the security, usability and deployment aspects of our solution.