A method of communicating between an Internet of Things device and a remote computer system, the method comprising: receiving in the Internet of Things device a secured data package from a mobile communication device via a close range communication circuit; decrypting in the Internet of Things device the secured data package, using a cryptographic key stored securely in the Internet of Things device; extracting in the Internet of Things device from the secured data package an identifier of a back-end system associated with the remote computer system, and storing the identifier of the back-end system in the Internet of Things device; transmitting via a the close range communication circuit an upload data message for the remote computer system from the Internet of Things device to the mobile communication device, within the close range of the Internet of Things device, for forwarding to the remote computer system via a mobile radio communication network, the upload data message including a unique identifier of the Internet of Things device and the identifier of the back-end system stored in the Internet of Things device; receiving in the remote computer system the upload data message from the Internet of Things device, as forwarded by the mobile communication device via the mobile radio communication network; storing in the remote computer system an address of the mobile communication device, as a communication relay address, linked to the unique identifier of the Internet of Things device; transmitting via the mobile radio communication network a download data message for the Internet of Things device from the remote computer system to the communication relay address linked to the unique identifier of the Internet of Things device, for forwarding to the Internet of Things device; and receiving in the Internet of Things device the download data message from the remote computer system, as forwarded by the mobile communication device via the close range communication circuit. receiving in the Internet of Things device a secured data package from a mobile communication device via a close range communication circuit; decrypting in the Internet of Things device the secured data package, using a cryptographic key stored securely in the Internet of Things device; extracting in the Internet of Things device from the secured data package an identifier of a back-end system associated with the remote computer system, and storing the identifier of the back-end system in the Internet of Things device; transmitting via a the close range communication circuit an upload data message for the remote computer system from the Internet of Things device to the mobile communication device, within the close range of the Internet of Things device, for forwarding to the remote computer system via a mobile radio communication network, the upload data message including a unique identifier of the Internet of Things device and the identifier of the back-end system stored in the Internet of Things device; receiving in the remote computer system the upload data message from the Internet of Things device, as forwarded by the mobile communication device via the mobile radio communication network; storing in the remote computer system an address of the mobile communication device, as a communication relay address, linked to the unique identifier of the Internet of Things device; transmitting via the mobile radio communication network a download data message for the Internet of Things device from the remote computer system to the communication relay address linked to the unique identifier of the Internet of Things device, for forwarding to the Internet of Things device; and receiving in the Internet of Things device the download data message from the remote computer system, as forwarded by the mobile communication device via the close range communication circuit.