A communication system is disclosed in which a communications node allocates resources for potential use by any of a plurality of user communication devices, including first type (e.g. legacy) user communication devices and second type (e.g. machine-type) communication devices. Control data is sent, to the user communication devices, defining communication resources for potential use by any of the user communication devices. The control data includes information identifying a first PRACH resource configuration for a first type user communication device and a second PRACH resource configuration for a second type of device such that the user devices can be distinguished by the PRACH configuration used.