Again Issue with Gs interface..
Android Os phone,when switched on,comes directly in PTM mode,
Now when there is not transaction within certain period(Say till detach time),SGSN detach the Ms..Mean While,MSC will also detach the MS with flag ISGSN(Implicit detach by SGSN)
Now if someone try to call that MS then it will be sound as un-rechable..!!
While in nokia Handset,there is a mode called Always Online & Whenever Needed…So not having this issue..
Only Android Phone are having the issue…