The objective of this Technical Report is to study and specify potential modifications to the ICS architecture in order to
enable all services to be controlled via IMS rather than via CS legacy mechanisms (single service domain), for all
subscribers of a network and also for inbound roamers.
As part of Release 8, 3GPP developed the concept of IMS Centralized Services which was then further extended in
Release 9. While the goal of ICS was to enable an operator to provide communication services (such that all services
and service control are centralized based on IMS mechanisms) on a per-subscriber basis, it has however not seen
widespread deployment, as support of both domains is still necessary.
To achieve the goal of fully centralizing services and service control in the IMS domain, network based solutions will
be studied that address the key issues and architectural assumptions defined in this document. In addition, these
potential solutions will be evaluated against the existing mechanisms available in 3GPP technical specifications, before
deciding whether to make changes to the relevant technical specifications.