The concept was used by PABX manufacturers as the basis of families of products in which the PBX would supply data connectivity and applications along with its traditional voice services.
[1] The office controller would be a central switch which would link users to applications and provide necessary services such as security.
As a result, the centralised model supported by the office controller fell out of style.
Remnants of the idea, with examples such as thin clients and three-layer architectures, did persist with some interest.
With the development of SIP with its session border controllers and service-oriented architectures, the centralized creation and management of user services is again finding widespread interest.