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Call Setup Time

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #47755

    How can we improve call setup time? What are the main areas have to be considered?

    What are the typical call setup times in following cases?

    GSM to GSM same network
    GSM to GSM – two networks
    GSM to PSTN

    Gito Prastomo

    Hi Mahesh,

    Call setup time is difficult to improve. But normal call setup time mobile to mobile is about 7 – 8s in GSM.
    You could breakdown the call setup from the L3 message, so you could rectify the problem, where is the long time to take? is it on the radio side or core interuption side.
    The problem I found like, the authentication occure very often (it must be tuned),some feature in MSC is activated, like IMEI check which take about 0.5s( could be tuned), RACH collision on radio interfaces (could be tuned)
    Some feature on MSC could be activated like off air call setup to improve call setup time.
    Another way is, the MTC number must in the same location (the MTC number must be the same location with HLR). Hope will help.

    javed shaikh

    In telephones the instrument has dedicated lines connected till the exchange whereas Mobile sends periodic information.
    We need much more technical answers to testify.
    Why do mobile phones dont have dial tones?


    Hi Gito Prastomo,

    Thanks for your important comment. I will try to implement your suggestions.


    Try to reduce the MFRMS. I did it once and managed to reduce the setup time by almost 1.5 seconds.
    old value was 5 vs. 4 as a new value.

    Disadvantages, MS more frequently listen to his paging group and may lead to a faster battery consumption if set to very low values.

    Good Luck


    Iam have assighnment failures after the alerting phase.I have available TCH to call to ride on.What could be the problem?


    It means the MS cannot access the TCH that was allocated by the BTS. Possible problem :

    – HW problem :
    —TRX BCCH in one sector, TRX TCH on another sector
    — poor TX or poor RX of TRX TCH (Path balance)

    – SW problem :
    — some timeslots cannot be allocated in the TRX (?)

    – Radio problems :
    — Poor coverage
    — High interference on the TCH frequency, whereas the SDCCH frequency is clean
    — Too much GPRS traffic –> TS are allocated as PDCH, therefore no more TS for voice. Maybe the PDCH are kept alive for a duration too long after the transfer has been finished.




    Thanks PIX

    Javed Shaikh

    1.In which format does mobile phone sends dialled numbers to BTS.

    2.why there is no dial tone in mobile phones?



    1. phone number is sent during the SDCCH phase, in the DTAP message “SETUP” (field “called party number”), after “AUTHENTICATION” and “CIPHERING”.
    The format of the phone number is decimal. Of course it is ciphered, but in the K12 trace, you can read it directly (example : “+33064544454” for an international number)

    2. there is a dial tone in the mobile. if there is no dial tone, it might be because the message “ALERT” (from MSC to MS) doesn’t contain a valid “ring tone information” (to be verified, i can’t be sure about this)
    The message ALERT is sent at the end of the call setup, after the “ASSIGNMENT COMPLETE” message (= TCH successfully allocated)



    RACH collision on radio interfaces MEANS WHAT

    Basha Shaik


    What is the recommended call set up time in GSM. I observed that it was 6 Sec in my N/W.

    How can i reduce it?


    …but checking which procedure is the taking time more than expected and deep dive…

Viewing 13 posts - 1 through 13 (of 13 total)
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