Recommend that you look at Ericsson’s website. FNR started out as a solution to scale HLRs. FNR, like a DNS, was used to resolve which HLR supported your subscription. Later on FNR was used as an input for MNP solutions using a Signalling Relay Function. Ericsson FNR is flexible and can be deployed with the HLR or the core Signalling Network.
VBR/ Wallis Dudhnath