When a user obtains an IMS subscription from an operator, the operator needs to assign a user profile. The user profile contains at least one private user identity and single service profile. Figure 3.19 depicts the general structure of a user profile [3GPP TS 29.228]. The private user identity was described in Section 184.108.40.206, but it should be understood that a user profile may contain more than one private user identity, if a user is using a shared public user identity as described in Section 3.7. Figure 3.4 shows that a single IMS subscription may contain multiple service profiles; this allows different treatment for different public user identities as explained in Section 220.127.116.11.
A service profile is a collection of user-specific information that is permanently stored in the HSS. It is transferred from the HSS to an assigned S-CSCF in two user data-handling operations – Server-Assignment-Answer (SAA) and Push-Profile-Request (PPR) – as described in Sections 18.104.22.168 and 22.214.171.124. The service profile is carried in one Diameter AVP, where it is included as an Extensible Markup Language (XML) document. The service profile is further divided into three parts:
Core Network Service Authorization;
Initial Filter Criteria.