 P-Asserted-Identity:<sip:alice@homel.net> Originating identification restriction (OIR) consists of hiding Alice's identification from the callee (Bob). 158 VoLTE and ViLTE Alice's UA entity can temporarily mask the presentation of her identity. It has to perform the following operations: - it has to fill in the header From with the following value: <sip:anonymous@anonymous.invalid> - it has to indicate the value id in the header Privacy SO that the identity present in the header P-Asserted-Identity - is not presented to INVITE sip: :bob@homeB.net SIP/2.0 From: "anonymous" <sip:anonymous@anonymous.invalid>;tag=xy: P-Asserted-Identity:<sip:alice@homel.net> Privacy:id If Alice has subscribed to OIR, her telephony application server has to insert the value id into the header Privacy. It also has to modify the value of the header From to erase Alice's identity. If Alice has subscribed to OIR, Alice's UA entity can raise the restriction temporarily by inserting the value none in the header Privacy. If Bob has not subscribed to OIP or if the header Privacy has the value id, his telephony application server has to remove the header P-Asserted-Identity, modify the value of the header From and remove Alice's identity. 5.2.1.2.2. TIP and TIR Terminating identification presentation (TIP) consists of showing Alice, in the response 183 Session Progress, the identity of the callee (Bob or Carol in the case of communication forwarding), certified by the IMS network. SIP/2.0 183 Session Progress P-Asserted-Identity: - <sip:bob@homeB.net> Service Profiles If Alice has not subscribed to TIP or if the messages received contain the header Privacy with the value id, her telephony application server has to remove the header P-Asserted-Identity - and modify the value of the header From, deleting Bob's or Carol's identity. Terminating identification restriction (TIR) consists of hiding Bob or Carol's identity from Alice. The callee's UA entity (i.e. Bob's or Carol's) can temporarily mask the presentation of his/her identity by adding th