A communication system, comprising: a network entity of a communication network; a core network connected to the network entity; at least one Narrowband Internet of Things, NB IoT, communication device (110a-d) coupled to the communication network via the network entity, wherein the NB IoT communication device (110a-d) includes a real-time operation system, ROTS, which is coupled to a sensor that provides the ROTS with measurement data, and wherein the at least one NB IoT communication device (110a-d) is configured to transmit measurement data (133, 134, 135, 136) via the network entity to the communication network; a block chain, configured to store a code associated with the at least one NB IoT communication device (110a-d), wherein the code entitles the at least one NB IoT communication device (110a-d) to transmit the measurement data (133, 134, 135, 136) to the communication network, wherein the network entity is configured to request (132, 161) the block chain for the code of the at least one NB IoT communication device (110a-d), to check the code with respect to a predefined validation criterion and to enable the at least one NB IoT communication device (110a-d) to transmit the measurement data (133, 134, 135, 136) via the communication network if the code is valid, wherein the block chain is configured to update the code based on the at least one measurement data transmission (133, 134, 135, 136) of the at least one NB IoT communication device (110a-d), wherein the block chain is configured to create a new entry responsive to the at least one measurement data transmission (133, 134, 135, 136) of the at least one NB IoT communication device (110a-d), and wherein the new entry comprises an identification of the at least one NB IoT communication device (110a-d), an updated code and a cryptographic function, in particular a hash value, of a preceding entry in the block chain, wherein the code comprises an amount of chargeable resources; and wherein the block chain is configured to update the code based on decrementing the amount of chargeable resources upon the measurement data transmission (133, 134, 135, 136) of the at least one communication device, wherein the at least one NB IoT communication device (110a-d) carries a pre-paid credit in a security area, wherein the pre-paid credit is transported in a credit counter together with the measurement data to the core network, wherein the core network performs a plausibility check of the pre-paid credit with the code of the block chain. a network entity of a communication network; a core network connected to the network entity; at least one Narrowband Internet of Things, NB IoT, communication device (110a-d) coupled to the communication network via the network entity, wherein the NB IoT communication device (110a-d) includes a real-time operation system, ROTS, which is coupled to a sensor that provides the ROTS with measurement data, and wherein the at least one NB IoT communication device (110a-d) is configured to transmit measurement data (133, 134, 135, 136) via the network entity to the communication network; a block chain, configured to store a code associated with the at least one NB IoT communication device (110a-d), wherein the code entitles the at least one NB IoT communication device (110a-d) to transmit the measurement data (133, 134, 135, 136) to the communication network, wherein the network entity is configured to request (132, 161) the block chain for the code of the at least one NB IoT communication device (110a-d), to check the code with respect to a predefined validation criterion and to enable the at least one NB IoT communication device (110a-d) to transmit the measurement data (133, 134, 135, 136) via the communication network if the code is valid, wherein the block chain is configured to update the code based on the at least one measurement data transmission (133, 134, 135, 136) of the at least one NB IoT communication device (110a-d), wherein the block chain is configured to create a new entry responsive to the at least one measurement data transmission (133, 134, 135, 136) of the at least one NB IoT communication device (110a-d), and wherein the new entry comprises an identification of the at least one NB IoT communication device (110a-d), an updated code and a cryptographic function, in particular a hash value, of a preceding entry in the block chain, wherein the code comprises an amount of chargeable resources; and wherein the block chain is configured to update the code based on decrementing the amount of chargeable resources upon the measurement data transmission (133, 134, 135, 136) of the at least one communication device, wherein the at least one NB IoT communication device (110a-d) carries a pre-paid credit in a security area, wherein the pre-paid credit is transported in a credit counter together with the measurement data to the core network, wherein the core network performs a plausibility check of the pre-paid credit with the code of the block chain.