Describes requirements for particular functions of subscriber's apparatus for connection to the British Telecommunications public switched telephone network. Applies to both speech and non-speech apparatus for connection to exclusive lines. Does not apply to simple extension telephones without additional facilities, nor to modems without additional facilities. Covers abbreviations and definitions, safety, connection to the PSTN, electrical characteristics, telephone apparatus, modems, facilities and functions of products, marking, information to be provided by the supplier and test requirements.