The Customer Service System (CSS) of the

BT Group BT Group plc (trading as BT and formerly British Telecom) is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, broa ...

(previously British Telecommunications) is the core operational support system for BT, bringing in 70% of income for the company (figures from 1997). BT rolled out CSS nationally in 1989 and provided an integrated system for telephony—order handling, repair handling and billing. BT Customer Service System (BT/CSS) was developed by

Logica Logica plc was a multinational IT and management consultancy company headquartered in London and later Reading, United Kingdom. Founded in 1969, the company had offices in London and in a number of major cities across England, Wales and Scot ...

in 1984, costing £1bn to implement, representing the largest computer project undertaken in Europe and the largest integrated database in the world, at the time. In 2005, the CSS databases deployed by BT handled 23 million customers, with 13 terabytes of data spread out over 28 mainframe images. The databases supported 230 million transactions per day generated by over 40,000 users. CSS is still used by BT but it is now controlled by Openreach. BT retail migrated all accounts from CSS to a new billing system known as Geneva/Oneview/Avalon. This was to support the migration to WLR3.

References

{{BT Group Telecommunications systems BT Group