Building technology device communication system, comprising at least one border router comprising a first network interface configured to connect to an external network, and a second network interface configured to connect to an IoT-network, wherein the at least one border router is configured to logically and/or physically connect the external network to the IoT-network, a plurality of IoT-network devices in the IoT-network connected to the at least one border router, wherein the plurality of IoT-network devices each comprises identifier information data, and are configured to send the identifier information data to the at least one border router, a remote server configured to receive the identifier information data from the at least one border router, and to associate the received identifier information data with corresponding authorization data stored at the remote server, and a commissioning device configured to obtain the identifier information data from the at least one border router and the authorization data associated with the identifier information data from the remote server and to commission the plurality of IoT-network devices using the identifier information data and the authorization data, wherein the commissioning is characterized in that the IoT network further comprises at least one already commissioned IoT network device and the plurality of IoT-network devices is adapted to operate in an ad-hoc communication mode and to register identifier information with respective link local neighbors wherein the at least one already commissioned IoT-network device is configured to receive the identifier information data of link local neighbors and to send the identifier information data with a signal strength indicator of the link local neighbors to the at least one border router, the at least one border router is configured to collect the identifier information data and the signal strength indicators, to generate a list of the identifier information data including the signal strength indicators and to send the list to the commissioning device, and the commissioning device is configured to selectively allow IoT-network devices of the plurality of IoT-network devices to join to the IoT-network based on the signal strength indicators in the list. at least one border router comprising a first network interface configured to connect to an external network, and a second network interface configured to connect to an IoT-network, wherein the at least one border router is configured to logically and/or physically connect the external network to the IoT-network, a plurality of IoT-network devices in the IoT-network connected to the at least one border router, wherein the plurality of IoT-network devices each comprises identifier information data, and are configured to send the identifier information data to the at least one border router, a remote server configured to receive the identifier information data from the at least one border router, and to associate the received identifier information data with corresponding authorization data stored at the remote server, and a commissioning device configured to obtain the identifier information data from the at least one border router and the authorization data associated with the identifier information data from the remote server and to commission the plurality of IoT-network devices using the identifier information data and the authorization data, wherein the commissioning is characterized in that the IoT network further comprises at least one already commissioned IoT network device and the plurality of IoT-network devices is adapted to operate in an ad-hoc communication mode and to register identifier information with respective link local neighbors wherein the at least one already commissioned IoT-network device is configured to receive the identifier information data of link local neighbors and to send the identifier information data with a signal strength indicator of the link local neighbors to the at least one border router, the at least one border router is configured to collect the identifier information data and the signal strength indicators, to generate a list of the identifier information data including the signal strength indicators and to send the list to the commissioning device, and the commissioning device is configured to selectively allow IoT-network devices of the plurality of IoT-network devices to join to the IoT-network based on the signal strength indicators in the list.