Please find my comments in-lined.
1.I want to know more specifically how VMSC forwards this USSD to HLR ?
The MS-initiated USSDReq includes IMSI, which will be used to forward the USSDReq to HLR.
2.Is is possible to explain how the analaysis is done in ERICSSON-HLR ?
Sorry, no idea……… but let me add what i think the possibility can be!!.
The HLR should be allowed to configure USSDgw for specific services. When USSDReq received with specific service, the same will be forwarded to USSDgw.
Hope this helps…..