A diagnostic device for a communications network; the network comprising a customer communications network located at a customer location and connected by a customer communications link to a communications service provider network remote from the customer location. The device comprises a network monitoring interface arranged to monitor operation of the customer communications network; a processor arranged to detect faults in the operation of the customer communications network, a store for storing records of detected faults; a processor arranged to store records of detected faults in the store and to generate a report on a detected fault based on the stored records. The device is co-located with the customer communications network and further comprises: a first communications interface arranged to send to the communications service provider network via the customer communications link, the report generated on the detected fault; and a second communications interface arranged to send to the communications service provider network via a second communications link, the report generated on the detected fault.