We are working on a HSS project for a client and are stuck in a strange issue. Right now we are in POC stage.

When we send ULA to MME, right after it MME sends PUR to us for the same subscriber and the UE does not attach to network (obviously). MME is not under our control (roaming partner) so we cannot get the logs from it.

We have tried to imitate ULA as per another working UE in same roaming partner network (this connects to live HSS, not ours) and it did not work.

Can anyone please guide what could be wrong?

Please let me know if you need more information.