Lot of our customer complain that they are not reachable for incoming call, although their phone is on and status bar is swhowing full signal. It alwasy happens when UE is in dual mode.
I tried to trace it, but without results. Although UE doesn’t have any other connection in progress, it still could not be paged for incoming call. Just seconds after that, he receives a message about missed call.
What do you mean, Dual Mode ? 2G+3G ? Or 2G CS+PS ?
You need to ensure your UE are :
1/ doing periodic location update (T3212 = 4hrs for example)
2/ autonomously attach to the network when switched on (parameter “ATT” = ON)
3/ that the periodicity of location update (timer = T3212) on BSS side is shorter than periodicity of IMSI detach in VLR (timer = purge or detach timer)
Those are the basic rules. If they are done, but still no success, then deeper investigations must be performed. The interesting traces to do are @ A interface and/or IuCS level. Is the paging sent to the idle UE ? To which LAC specifically ?
When turning your MS on, does it perform an Attach, through a location update.
After few hours in idle mode, does it send a location update (periodic) ?
After few hours in idle, when trying to page this MS, does the MS receives the paging on the radio ?Does it try to reply ?
In BSS Counters, check out the follwoing counters, in an cell with such issue :
SDCCH established for Paging Response
SDCCH established for Location Update
SDCCH established for ATTACH or DETACH
Number of Pagings sent
Then compare those numbers with a “good” cell, if any. Are the ratio approximatively similar ?