Faults occurring on British Telecom’s Packet Switchstream, PSS, X25 dial-up access service are still under investigation, following an almost complete breakdown in service on September 30. Users trying to ring the majority of the 28 PSS exchanges, developed by Telenet in the US and installed by Plessey in the UK, were unable to get an answer from the exchanges. Others were able to get through but found that the exchange did not recognise their network user identity and would, therefore, not accept them as bona fide PSS subscribers. Fault report centres were jammed with telephone calls all day, although at least 400 calls regarding the faults were registered. Personnel at the fault report centres were surprised at the magnitude of the problem on a service that is generally fairly reliable. Telecom stresses that, although the problem has not yet been identified, it has established that the fault is neither the result of an equipment defect nor of capacity saturation on the service. It claims the service was back to normal by the end of the day, apart from two exchanges, Brighton and Cardiff, although one user says he was unable to access the Manchester exchange until 2.00 in the afternoon on October 1. Subscribers accessing the Brighton and Cardiff exchanges have been issued with free temporary network user identities, which will give them normal access to the service.