ofile. Each service profile includes one or more IMS public user identity (IMPU) in the form of an SIP URI or TEL URI and a service logic in the form of initial filter criteria (iFC) (Figure 5.2). Service Profiles The field "core network service authorization" of the service profile structure contains an integer number representing the type of media (audio, video) that the user has the right to negotiate in the session description protocol (SDP) message (Figure 5.2). Initial Filter Criteria User profile Priority Private User Identity 0 to 1 1 to n Service Profile n Trigger Point Service Profile 2 1 to n Service Point Trigger n Service Profile 1 Service Point Trigger 2 1 to n Public Identity n Service Point Trigger 1 Public Identity 2 Request URI SIP Method Public Identity 1 SIP Header Session Case Session Description 0 to n Initial Filter Criteria n Initial Filter Criteria 2 Application Server Initial Filter Criteria 1 SIP URI Default Handling Core Network Service Authorization Service Information Figure 5.2. Subscription data to the IMS network The first field of iFC data is priority, which determines the order in which the criteria need to be evaluated. The next field relates to the trigger point, which is a collection of filters (service point triggers) Each filter consists of a logical operation carried out on the basis of the following parameters: Request-URI: the value of the uniform resource identifier (URI) of the request; - SIP Method: the type of method of the request; - SIP Header: the content of the headers; 150 VoLTE and ViLTE - Session Case: the type of call (outgoing or incoming), for a registered or unregistered mobile; - Session Description: the content of the fields of the SDP message. The iFC data also contain the public identity of the telephony application server (TAS) to which the S-CSCF entity transfers the request if the conditions are all fulfilled. The field "default handling" defines the treatment that needs to be applied to the request (continuation or cessation) if the S-CSCF entity c