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30th July 2010 at 09:52 #63883ATTOGuest
We’ve got few numbers in our network trying all day long to access network. They got rejected by the network because IMSI is unknown from the HLR.
THE IMSI state in the HLR is “not connected”.
What can be done for thoses IMSI because they generate huge LU attempts then congestionning radios ressources SDCCH and SCCP ressources.
Thanks .30th July 2010 at 10:46 #63884pixGuest
interesting. i’m sure some people know better about this situation than I, but if i were in your position, i would check manually where those IMSI are coming from (were they sold in your country, in your operator, or elsewhere ?)
then you can check in which cells those bad IMSI are located (by doing A-interface trace, unless there is another solution ?)
pix30th July 2010 at 14:17 #63885ATTOGuest
We have captured A interface and saw exactly the value of IMSI.
other informations are also available : old MCC + MNC which comes from our network but the LAC value is from another network ( unknown network ).
We print (with NSS guys) , the state of those IMSI in the HLR but we’ve got same results : IMSI not connected. But all those IMSI are registered in AuC Center.
NSS guys told me that it can may be numbers that have been deleted because of subscribers not having done any “cost activity” for 3 months..
My problem is that i am BSS guy and I need to reduce SDCCH signaling in order to avoid congestion.
Thanks.30th July 2010 at 14:27 #63886ATTOGuest
For yesterday only,from 00:00 to 23:59 , we record 6870 LU failures done by thoses 3 IMSI. All LU failures with the same cause : IMSI unknown in HLR.
Thanks30th July 2010 at 14:37 #63887pixGuest
so you are in this weird situation:
you are asked to drive 100 passengers from A to B in a bus in less than 30 minutes, while singing great songs and providing a fantastic guide-tour performance.
but you don’t have a bus.
so how can you do all this if you don’t even have a bus ?
clearly, your BSS problem is just caused by this HLR misconfiguration. Your job is done here, report the problem and its root cause to your boss, and move on 🙂
pix30th July 2010 at 14:39 #63888PhoneGuest
Please do a trace and check the TAC number of the phones used by those IMSI.
If they use ZTE phones (A35 for example) then you have the same problem as some networks are facing now:
If a deleted Sim is inserted in some ZTE phones, it will send LU requests every approx 2 sec unless the person itself takes out the deleted sim from the phone or unless you create again the deleted sim and call the guy to stop.
Cheers30th July 2010 at 14:50 #63889ATTOGuest
Thanks for ur help guys.
Yeah, We have huge number of ZTE phones in our country.
I was thinking of some kind of solution coming from NSS guys by changing for example parameters in MSC -Server or HLR.
If it doesn’t exist, What can i do , nothing , just reporting the issue.
Thanks again.30th July 2010 at 14:50 #63890PhoneGuest
Of course it is the phones the root cause. They said there was bug in the software..
Hope it is not your case because it is difficult to withdraw 1000 phones from the market or recreate deleted sims everyday…
Cheers30th July 2010 at 18:16 #63891pixGuest
do you have an EIR in your network ? or any other way to know the IMEI of the phone making the LU ?
by knowing the IMEI you can detect the manufacturer of the faulty phones, see if it’s indeed ZTE or another one.
thanks phone, great info.30th July 2010 at 22:27 #63892ATTOGuest
I ll check this later pix. For now it is weekend . I need to relax otherwise i ll be crazy.2nd August 2010 at 13:15 #63893ATTOGuest
No EIR in my network , and Astellia captures from A interface seems not being able to provide IMEI number even if it is integrated through their analyser GUI ( Activity analysis ).
No other way for the moment to get IMEI information.
BR3rd August 2010 at 10:31 #63894PhoneGuest
You are right, IMEI is not sent in LU request messages, so no way to see the IMEI in the traces.
What you can do to check:
1. go to Astellia AA
2. open the latest AA base (real time analysis)
3. take distribution of IMSI doing the most failed LU – cause (Rej)IUH
4. Reactivate 5 of those IMSI with test numbers and call them immediately to know which phone they are using
5. Get the same phone to test yourself the scenario.
Cheers28th October 2010 at 12:44 #63895ANGuest
Hi Anno or Phone, we are facing the same issue with our customers and inbound roamers at our network ? what shall we do in order to prevent this kind of failure?26th March 2018 at 16:34 #63896AyatGuest
we are facing the same problem in our Network with ZTE and Huawei vendors
we delete inactive SIMs from HLR
we receive this error IMSI unknown in HLR” from HLR
and we notice huge LOC UP attempts and it effect the radio resources, it is clear under 2G netwrok more than 3G.