– the roming patners IMSI series & HLR GT should be defined in MSC.(same as like we do for normal roaming).
– those IMSI series should give permission in the corresponding Location Area (MSC/ BSC configuration)
Regarding call routing in ICR, you can go for the IMSI based call routing. ie, any MO request from the ICR customer should route to HPLMN based on IMSI based routing.