As you may know for LU (location update) in a 2G network, the VLR asks the HLR for subs data and the request is IMSI based.
In case there is more than one HLR, the operator has to split the IMSI ranges to point to the specific HLR.This brings some complications such as arrangements with the SIM card vendor on the IMSI ranges to use, spare SIMs in the shops for SIM replacements etc.
In order to prevent all this it is possible to put a SCCP Relay node in order to route the LU update requests to the proper HLR.
The SCCP Relay node is the database which contains IMSI/MSISDN pairs and the operator now can allocate MSISDN ranges to the HLRs and not IMSI ranges.
Now…is it possible to use the same SCCP Relay node to route RA update requests to the right HLR?
Is the RA update the same as LU update?