Ayat,
you said:
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1. T3213(periodical timer in Radio) = 174min
2. t(periodical timer in VLR) = 240min (large than T3213, so it is available if the T3213 is not successful)
3. purge timer = 24Hours
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the t(periodical timer in VLR) is at a good value, so IMO it means that the MS which are no more “available” are quickly marked as “detached” by the VLR.
So my previous recommendation is actually already done in your network 🙂
the purge timer would not influence your KPI (afaik).
i can’t help more…
pix