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UK: The new "System X"

01 March 1995

The new UK telephone network supports ISDN (Integrated Services Digital Network) which allows digital devices (eg: fax machines) to share the same system with existing phones. The ISDN sub-set that British Telecom (BT) uses is defined in their document, BTNR 191, "Signalling CCITT I-series interface for ISDN access". Built into the international CCITT protocol is the ability to take a phone "off hook" and listen to conversations near the phone without the user being aware of this happening. It has the same ability to eavesdrop on PABX phones - multiple lines in offices. BT states that this is not implemented in the UK. In the late 1980s "System X" was introduced in the telephone network this allowed all the calls made from and to a phone number to be logged. It allowed the standard surveillance of selected phones and all calls made - it now forms the itemised bills available to everyone. The "bugging" of conversations in a room with a phone required placing a "bug", or "infinity bug" in the phone itself. Due to the nature of the electronic connection in the new phone system there is no need for property to be entered to place the "bug", the system can do it automatically. SGR Newsletter, Issue 4, September 1993; Stranger on the Line, Patrick Fitzgerald and Mark Leopold,Bodley Head, 1987.