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CM Service Abort

Viewing 15 posts - 1 through 15 (of 16 total)
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  • #56253 Reply
    FR
    Guest

    We are having lot of Mobile originated CM Service Abort messages. Duration b/w CM Service Request and Abort is very low i.e less than 500ms.

    I want to know what is the cause of it. what type of call scenario can cause this.

    CM Service Type is
    0 0 0 1 Mobile originating call establishment or packet mode connection establishment

    #56254 Reply
    Mike
    Guest

    What is reason in the abort message?

    #56255 Reply
    ATTO
    Guest

    Hello,

    I have the same problem; Most of times it happens when the MSC send the ‘ciphering mode command’ message. Instead of completing the cipher mode, the BSC send the CM service Abort with no cause.
    I read from Astellia reports that it is the user who abort the call but i’m sceptic.

    #56256 Reply
    Pix
    Guest

    FR,

    ATTO method is good: when exactly the Abort is sent? There are plenty of DTAP msg after the CM Service Req (Ciphering, Call Setup, Identity, …)

    ATTO,

    Have you tried deactivating the ciphering for a while? Which cipher are you using? A5/3 perhaps?

    In the cipher mode cmd, the MSC sends a list of possible codecs, and it’s up to the BTS to choose one (depends on BTS capbilities and MS capabilities, received in a previous radio msg)

    Regards,
    pix

    #56257 Reply
    FR
    Guest

    Pix/Atto,

    The flow goes like this:

    CM Service Request (From Mobile)
    Connection Confirm (From MSC)
    Classmark Request (From MSC)
    CM Service Accept (From MSC)
    Classmark Update (From Mobile)
    CM Service Abort (From Mobile)
    Clear Command (From MSC)
    Clear Complete (From Mobile)
    Released (From MSC)

    Ciphering is not used in my case.CM Service is accepted by MSC and then mobile aborts it with no cause.

    There are lot of such call flows and no apparent reason is found.

    Atto,
    In which country are u using Astellia?

    #56258 Reply
    ATTO
    Guest

    Hi ,

    FR

    I have Ur case too. No reasons are found on the decoded frames.

    Pix,

    In the decoded signal that the MSC sent, this one support A5/1, A5/2 and A5/3. Our BSC support only two mode : A5/1 and A5/2.
    In some cases, the MS send the ‘ Classmark Update’ before the ‘CM service Abort’. I decode one of theses cases and see that the MS support the 3 cipher mode.

    For the information, no one have tried to deactivate ciphering.

    Regards!

    #56259 Reply
    Pan
    Guest

    Dear, Fr! What is the message – “Connection Confirm”? On what layer it is generated? MM? RR? or???
    Why your network does not use authentication?
    Is there general behavior of a number MS models or the only MS model?

    #56260 Reply
    Pix
    Guest

    If nobody complained and if you’re not able to reproduce the issue, then Astelia is probably right… People are stopping the call during teh call setup. Sounds Ok.
    It happens to me…

    #56261 Reply
    FR
    Guest

    Pan,

    Connection Confirm is ‘SCCP’layer message.

    Authentication is used in LU/IA. Normal call is initiated using TMSI.

    No specific mobile/number is affected. Such Abort messages come from different users/mobiles.

    Pix,

    I have tried to make several calls with immediate disconnect as fast as i can and then checked the traces. None of such calls landed with CM Service Abort. Such calls were with disconnect message from mobile after setup message. I am surprised who r these super fast people 😛 or maybe it is due to some automated application in mobile!!!

    Pix – 19 Mar 2009
    If nobody complained and if you’re not able to reproduce the issue, then Astelia is probably right… People are stopping the call during teh call setup. Sounds Ok.
    It happens to me…
    Pan – 19 Mar 2009
    Dear, Fr! What is the message – “Connection Confirm”? On what layer it is generated? MM? RR? or???
    Why your network does not use authentication?
    Is there general behavior of a number MS models or the only MS model?

    #56262 Reply
    Pix
    Guest

    Yes, Pan is right, the fact that there is no Authentication first is very weird. Is it standard that the Classmark request is done before everything else ?

    Pan > Connection Confirm and Connection Request are SCCP messages, aren’t they ? They exchange CIC identification on both ends (BSC and MSC), with link number and timeslot number.

    #56263 Reply
    FR
    Guest

    Pix,

    Classmark Request and Update messages are present in the flow. After Classmark update mobile sends CM Service Abort..

    #56264 Reply
    Pan
    Guest

    Yes, Pix, I know about SCCP Connection Confirm and Connection Request messages 🙂 FR-> On your place, I would fix this problem closer to MS, i.e. you need A-bis or Um message flows (not only A) because BSS analyse Classmark info, and order of the messages may be different from those you presented.

    #56265 Reply
    Bilal
    Guest

    CM Serv Abort is sent if the call ends before the setup msg. Atto you should check if the percentage is same for all the BSCs or one is more affected. If one of the BSC is heavily affected then it can be issue during the establishment

    #56266 Reply
    Ayat
    Guest

    Hi

    In my case, there is no CM Service Accept (From MSC) from the trace may there is another mesaage include it

    could you help me !

    #56267 Reply
    Hoang Lam
    Guest

    Dear
    I used Nemo to measure QoS and I’m facing some problem.
    Some one help me.
    1. What’s a call setup fail due CM_SERVICE_ABORT ?
    2. what’s a drop call due IMSI_DETACH_INDICATOR?
    thanks in advance

Viewing 15 posts - 1 through 15 (of 16 total)
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