
IMS: IP Multimedia Subsystem ◾ 257
established and built upon for each service. Once the IMS is in place, access to
other users’ services is an IMS network issue and this is common to all IMS per-
sonal services, as shown in Figure 13.9.
erefore, the requesting user’s operator service setup need not be involved in
routing the request. Another advantage is the freedom inherent in not having to
establish multiple inter-operator relationships for each service. e single-inter-
operator relation in the IMS is shown as a single line linking the operators. e
network-to-network relationship between the two operators is therefore established ...