British Rail received a visit the other day from the Union Internationale des Chemins de Fer, the international association of railway boards, which sent down an Integrated Services Digital Network working party to see a demonstration of Horsham, West Sussex-based Ericsson Ltd’s MD110 private branch exchange in a multi-vendor environment; the demonstration formed part of Ericsson’s on-going efforts to promote the use of the DPNSS signalling standard for digital private networks, a standard developed some time ago by British Telecommunications Plc in conjunction with the private branch exchange suppliers.