The cause code is : IMSI unknown in VLR

[eritelecom]

Hi all,

I faced a call rejection on a site 6 successive times !!
all of them are noted as "Call was released by the network via CM Service Reject Message"The cause code is : IMSI unknown in VLR
could any one help me resolving this issue ?
please note that the call was successfully established in the 7th attempt.
CPICH RSCP = -68, Ec/No = -5

Thanks a lot helpful friends

Eri

[shahram]

Hi,
You should chekc the Charging systesm (are you using pre-Paid sim card for drive testing?)
also check the TMSI allocation limits in core,you migh not have enought TMSI to be allocated to all subscribers.

BR

[zhanglw268]

What's the exact call sequence?
Was the mobile in a location area border?
Which vendor's MSC-VLR?

[riyantoyadi]

1. What number do you call? Mobile phone to Mobile phone or spesific number to make test call (operator served some number in MSS to make DT longcall)

2. Using post or pre (some operator using postpaid connected to IN like Prepaid)

3. handset/UE for Anum and Bnum on good condition?

[zhanglw268]

Is your RAN system using MSC pool function? If the MSCs in the pool malfunction, you may face this scenario in certain cells until your mobile does a location update successfully with one of MSC, then you can make call again.

[huaweiradio]

Hi

You need to see the IMSI Series , Is it belong to your own Network or Roamers. If Roamers might not be open in your MSC/VLR.

[kentck86]

I did encountered this issue at Inter-RNC border(Lets say i am crossing from RNCA to RNCB) where my IMSI was registered to VLR of RNCA, but call attempting was did on RNCB where my IMSI was not yet registered to its VLR yet and this leads to call attempt failure. I did perform idleQoffset2sn tuning to fasten the cell reselection at those area but it seems not much help for this issue to be resolve.

[kentck86]

Anyone can suggest on action for the resolve of this issue?

[takeiteasy612]

HI kentck86
Could you give me more detail, Are these two RNC belong to two different MSC? and which vendor of RNC and MSC, Because i've face the problem before when i cross the border of 2 MSC.

[kentck86]

HI kentck86
Could you give me more detail, Are these two RNC belong to two different MSC? and which vendor of RNC and MSC, Because i've face the problem before when i cross the border of 2 MSC.


It is in same MSC under Huawei network. Any advice?

[ahmedrad]

It is in same MSC under Huawei network. Any advice?

This usually happens when you are in a call under one MSC and at some point performed an inter MSC handover under MSC 2 .. since there is no location update during a call then your phone is going to wait until the call is over, once you hangup then the phone should perform a LU, if you try to make calls consecutively your phone won't have time to read the system information and figure out that it is under a new lac and start a location update procedure. I believe there is a parameter in the MSC that gives Location updates a higher priority than CS calls forcing the phone to perform a LU before making the call. Look it up with your core network team it should solve the problem