BT's Customer Service System (CSS) is the core operational support sys
tem for BT and brings in 70% of BT's income. It was rolled out nationa
lly in 1989 and provided an integrated system for telephony - order ha
ndling, repair handling and billing. It continues to grow in size and
scope to handle new products and services and increasingly is interfac
ed to other systems to facilitate automation of business processes. Th
e need to overcome its limitations drives an evolution process for the
system which is lending to the development of complementary platforms
with which CSS must interwork and which will eventually replace it.