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switching networks when roamin

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  • #67261

    HI every one
    i hope that i am not posting this in a wrong section .. but i really need some expertise.
    i am a first year telecommunication engee. student, and working on a school project. and i have a question regarding network roaming.
    let’s say you have Service provider 1, and you travel and connect to service provider 2 ( international roaming ), is it possible to switch the providers in way that service provider 2 become your local service provider for the period of time you are in that contry, with other ords so when making a call, you dont need to connect to Service provider 1 ( since now SP2 is your your LSP ). all that without switching your SIM.

    i know it is a kind of confusion, that’s why i am asking for help so it can be clarified … but i hope that made sens. Any help will be appreciated. Thanks


    imsi is used to make Location update and consist of MCC + MNC + MSIN

    MCC + MNC are unique for every operator, Provider.

    So i think that without sim card switching it is not possible,

    be sure that you will not see any example like operators in your question.



    @Alonewolves .. thanks for the answer, i know that the IMSI code is unique to the Sim card, and it is hard coded inside the SIM card.

    But can the IMSI be changed ? with other words it detects in wich country you are on, and then using a script the IMSI is updated “over the air”. And supposing that the updated IMSI is already valid, then you are not international roaming anymore, it is correctly understood ?
    i know that you can change the IMSI using OTA programming, and maybe it can be done “over the air” .. but is the hole idea faisable, it is just i have to discuss that in my school project.



    what is the benefit of doing this ? what’s the benefit for an operator ?

    the imsi could be welcomed into a foreign operator, and be treated as a local one, if both local and foreign operators agreed (HLR will do the sync’)

    there is no need to change IMSI.



    Hi mounim,

    Pix is right,

    somehow you change the imsi on-air,

    HLR stores all subscriber info including security data of subscribers, (Ki)

    whether you can change the imsi successfully or not
    you will not be able to location update in roaming regarding the security issue.

    so to change the imsi from local to foreign operator’s , don’t let you to use your sim card in foreign operator.


    SIM can contain multiple IMSIs used for roaming to get roaming SP local call rates – bluefish an example.

    As PIX mention HLR sharing possible

    Some SIMs can also have security status of SIM in ATR so handset knows soonest what security SIM works with.

Viewing 6 posts - 1 through 6 (of 6 total)
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