The idea is that BT customers will have protection across enterprises, whether data is in the cloud, on site, or in hybrid IT systems.
BT said that its Assure Cloud Identity will securely connect employees, customers and partners to applications using any device.
The service will be hosted and available first in the UK at data centres, and BT will roll it out to mainland Europe later, as well as to other territories worldwide.
Mark Hughes, who runs BT Security said that CA had been a security partner for his company for over 10 years. The managed service will be provided to customers without them having to make capital investments in hardware or by hiring additional staff.