OIP and OIR have been around for a long time in the legacy world. So, it is no surprise that they have been standardized as part of the IMS architecture.
Even though supplementary services are call control telephony services, and should logically be the part of the CSCF, but they have been pushed to the IMS application layer in the form of a MMtel server.
The OIP service enables the called party to receive a network generated and trusted identity of the calling user on the screen of the mobile device. The originating user may also present a custom identity to be seen at the called party. The user generated identity is usually screened by the network of the originating user.
The OIR service is invoked when the calling user does not want their identity to be shown to the called party. In such cases, the network of the originating user signals to the network of the called user, to withhold the identity of the calling user.
Both these services are pretty basic in nature, and are being used almost with every mobile phone call we make !
