BS EN 50065-1. Signalling on low-voltage electrical installations in the frequency range 3 kHz to 148,5 kHz. Part 1. General requirements, frequency bands and electromagnetic disturbances
Apparatus for connection to public telecommunications systems using the Digital Access Signalling System No. 2 (DASS 2) via a 2048 kbit/s CCITT Recommendation G.703 interface-Specification for automatic-repeat call attempt facilities
