NO IMMEDIATE ASSIGNMENT problem

[erastus]

I experienced this problem several times:
Problem: When doing GSM drive test MS A(Calling party)gets nothing(no alerting) but the MS B (called party) gets a missed call alert for a very short duration & the same time TEMS shows blocked call (whereas layer 3 message shows "NO IMMEDIATE ASSIGNMENT" or "MISSING IMMEDIATE ASSIGNMENT" what does it mean?

Has anyone experienced the same problem and how to solve?

[tharinduwije]

May be due to congested MSC (Block calls normally occur for invalid Circuit assignment). Did you check Abis failures & reversions? Find the attached Huawei document for IMA SR troubleshooting.

08 GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manual.rar