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No call attemt

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  • #65437

    MS1 call MS2 (same network).
    MS1 has:
    Channel Request
    Immediate Assignment
    Call Proceeding
    Assignment Command
    Assignment Complete
    Alerting (DL)
    Call Setup
    (Setup time~18.5s)
    while MS2 has no Call Attemp (no Channel Request, just Cell Reselection).
    In this case, call failed.
    Anyone let me know the cause and solution. Thanks.

    Disconnect msg:
    Time: 09:27:11.98
    Frame number: 372727

    MsgCtrlOperation :
    Transaction identifier : 8
    Protocol discriminator : (3) Call control; call related SS messages
    Message type : 37
    Coding standard : (3) Standard defined for the GSM PLMNS
    Location : (0) user
    cause value : (16) Normal call clearing


    Hi, anh
    MS2 probably have active diverts.
    So in this situation scenario is:
    MS1 calls, MSC sends Paging to MS2 but MS2 at the same moment does cell reselection so he doesn’t “hear” paging. Call is devirted. As you see in Disconnect message, call have not failed, it have Normal call clearing so MS1 just ended call when he heard Voice mail or some IVR answer.
    This is normal case, especially if MS2 is using dual mode because some phones very often does cell reselection between 2G and 3G so chances of missed call for them are high.



    if there is an alerting message in DL for MS1, it means the MS2 is ringing… are you sure that the phone number you are calling is the MS2 ?

    If yes, then it means the MSC is actually answering the phone instead of the MS2. So that corresponds to a call being diverted to the voice mail directly. That could be a special setting of MS2, or just that the MS2 cannot be paged by MSC.

    I doubt that MS2 would miss the paging because of cell reselection ! The pagings are repeated by MSC, to avoid such case.

    Is MS2 IMSI-attached ?



    first consider these procedure for mSa calls Msb under same MSC
    1.Setup (BSSmsa to MSC)
    2.SRI (MSC to HLR)
    3.PRN (HLR to MSC )
    4.Call proceeding (MSC to BssmSa)
    5.Paging (msc to MSb)
    7.Setup (msc to bsc b)
    8.Call confirmed\
    MS operates in two modes: idle mode and dedicated mode. Cell reselection is performed as MS traverses through a network in idle mode. in dedicated mode it is called Handover. So reselection here means in IDeal and should not be considered. B can not be paged ! may be due to CFN but anyhow you receive release lets think it is not due to CFN.
    try to find out in which step you face with problem if you are @ BSS make sure whthere BSC receive Call proceeding message or not. This issues can be followed up by step 1 to 7, each step has it own way.
    call release with cause code Noraml can be mapped by many abnormal casesed in BSS side, for example if B can’t be given radio or radio interfrence msc would release call with
    cause code Noraml. with what being said , Put two numbers in core trace , very easily you will find problem 😉


    Hi all,
    Why the MS does cell reselection, it doesn’t listen to paging? It use PCH for paging.
    I check with drive test team, he just put the 2 MSs in GSM mode, no UMTS.
    I will update the status…



    the cell reselection with location update is too short and too rare that I doubt the MS will miss its paging message during that time. It could happen, but the probability is too low.

    But even if it does happen, then the MS will catch the next paging retransmission.


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