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IMSI Unknown in HLR

Ayat - 26th March 2018  (16:34 GMT)

Hello all

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.

AN - 28th October 2010  (12:44 GMT)

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?

Phone - 3rd August 2010  (10:31 GMT)

Hi Atto

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.


ATTO - 2nd August 2010  (13:15 GMT)

Hello Pix,

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.


ATTO - 30th July 2010  (22:27 GMT)

I ll check this later pix. For now it is weekend . I need to relax otherwise i ll be crazy.

pix - 30th July 2010  (18:16 GMT)

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.

Phone - 30th July 2010  (14:50 GMT)

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...

ATTO - 30th July 2010  (14:50 GMT)

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.

Phone - 30th July 2010  (14:39 GMT)

Hi Atto

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.

pix - 30th July 2010  (14:37 GMT)


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 :)


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