SDX was originally owned by STC which became part of Nortel.  This part of Nortel was bought as a management buyout.

It is thought that BT pushed the sale because Nortel was supplying BT with small and large telephone systems and that this could cause a conflict of interests.

SDX was then run by it's own management which strengthened the SDX range and bought out the Index range.

Lucent then bought the company and marketed the Index range for a period of time.

Lucent then changed the name of the telephone systems side of the business to Avaya.

Lucent then dropped all the SDX range and even the Index system is now obsolescent.

BACK Home page BT/GPO Telephones Search the Site Glossary of Telecom Terminology Quick Find All Telephone Systems

Last revised: January 28, 2023