LIR/LIA Lookup to Home Subscriber Server from I-BCF

The Oracle Communications Session Border Controller, acting as an I-BCF, can perform a Location Information Lookup (LIR) to a Home Subscriber Server (HSS) to find the S-CSCF where to forward a request message. LIR/LIA messages are part of the Diameter Cx interface, which is used to communicate with HSS.

In an IMS environment, a user registers with S-CSCF and that S-CSCF assigns itself with an HSS as the serving registrar for that user. When a call needs to be routed to the user, an I-BCF performs a location information lookup to the HSS to determine the S-CSCF for that user and route the request toward that S-CSCF.