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  1. #1
    I want to know how a gsm mobile gets connected to its network for the
    first time when it powered up for the first time given there are six
    other gsm operators working. Can anyone help me out?




    See More: GSM Booting sequence




  2. #2
    Jonathan Wilson
    Guest

    Re: GSM Booting sequence

    [email protected] wrote:
    > I want to know how a gsm mobile gets connected to its network for the
    > first time when it powered up for the first time given there are six
    > other gsm operators working. Can anyone help me out?

    The SIM card contains unique information identifying the specific operator
    which the phone uses to connect to that operators towers.



  3. #3
    k00L
    Guest

    Re: GSM Booting sequence

    thanks but on which channel the mobile send the information
    Jonathan Wilson wrote:
    > [email protected] wrote:
    > > I want to know how a gsm mobile gets connected to its network for the
    > > first time when it powered up for the first time given there are six
    > > other gsm operators working. Can anyone help me out?

    > The SIM card contains unique information identifying the specific operator
    > which the phone uses to connect to that operators towers.





  4. #4
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    "k00L" <[email protected]> wrote in message
    news:[email protected]...
    > thanks but on which channel the mobile send the information
    > Jonathan Wilson wrote:
    >> [email protected] wrote:
    >> > I want to know how a gsm mobile gets connected to its network for the
    >> > first time when it powered up for the first time given there are six
    >> > other gsm operators working. Can anyone help me out?

    >> The SIM card contains unique information identifying the specific
    >> operator
    >> which the phone uses to connect to that operators towers.

    >


    I'd tell you to do your own homework but with the state of Australian
    universities these days no doubt you'll just plagiarise it from somewhere
    else. And others here may be interested.

    GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
    down to is that the SIM keeps a 'cache' of the last known location area and
    allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
    The SIM also has a stored preferred and forbidden PLMN list of network codes
    to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
    the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
    With a smartcard reader you can also inspect the contents of the EFBCCH file
    to see what ARFCN channel numbers (frequencies) your network uses.

    Basically, when your phone is turned on, all of these cached parameters are
    used in some way to optimize the search for the home network. If this
    network can't be found, then the phone tries other networks until it
    successfully is able to IMSI-attach ("login") to one of them. This is how
    roaming works.

    As for which channels the mobile uses for 'connecting' to the GSM network
    (which is not really the correct term, as at most a location update is
    performed and then the mobile returns to idle mode) - there are several
    used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
    technically involved. However, the two main channels of interest are the
    BCCH where all sorts of information about the network is constantly
    broadcast over and over again (allowing mobiles to decide which cells to
    camp on, whose network it is, etc, etc) - this is how the MS identifies a
    candidate cell. Then, when it wishes to IMSI-attach/location update, it will
    do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
    for most non-voice/data connections (mobility functions, SMS, setting up a
    voice call, etc).





  5. #5
    Nole Boaday
    Guest

    Re: GSM Booting sequence

    Jeremy Quirke wrote:
    > "k00L" <[email protected]> wrote in message
    > news:[email protected]...
    >> thanks but on which channel the mobile send the information
    >> Jonathan Wilson wrote:
    >>> [email protected] wrote:
    >>>> I want to know how a gsm mobile gets connected to its network for the
    >>>> first time when it powered up for the first time given there are six
    >>>> other gsm operators working. Can anyone help me out?
    >>> The SIM card contains unique information identifying the specific
    >>> operator
    >>> which the phone uses to connect to that operators towers.

    >
    > I'd tell you to do your own homework but with the state of Australian
    > universities these days no doubt you'll just plagiarise it from somewhere
    > else. And others here may be interested.
    >
    > GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
    > down to is that the SIM keeps a 'cache' of the last known location area and
    > allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
    > The SIM also has a stored preferred and forbidden PLMN list of network codes
    > to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
    > the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
    > With a smartcard reader you can also inspect the contents of the EFBCCH file
    > to see what ARFCN channel numbers (frequencies) your network uses.
    >
    > Basically, when your phone is turned on, all of these cached parameters are
    > used in some way to optimize the search for the home network. If this
    > network can't be found, then the phone tries other networks until it
    > successfully is able to IMSI-attach ("login") to one of them. This is how
    > roaming works.
    >
    > As for which channels the mobile uses for 'connecting' to the GSM network
    > (which is not really the correct term, as at most a location update is
    > performed and then the mobile returns to idle mode) - there are several
    > used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
    > technically involved. However, the two main channels of interest are the
    > BCCH where all sorts of information about the network is constantly
    > broadcast over and over again (allowing mobiles to decide which cells to
    > camp on, whose network it is, etc, etc) - this is how the MS identifies a
    > candidate cell. Then, when it wishes to IMSI-attach/location update, it will
    > do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
    > for most non-voice/data connections (mobility functions, SMS, setting up a
    > voice call, etc).
    >


    I'm curious as well on this topic. So there's a specific
    frequency/channel that is shared between all mobile providers around the
    world in which they continually broadcast their network details?

    I’ve always been curious as to how you can take your GSM phone to a
    different country, with different networks running of different
    frequencies (well, deviations from ~900Mhz say), and still pick one of
    them up.




  6. #6
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    Nole Boaday wrote:
    > Jeremy Quirke wrote:
    > > "k00L" <[email protected]> wrote in message
    > > news:[email protected]...
    > >> thanks but on which channel the mobile send the information
    > >> Jonathan Wilson wrote:
    > >>> [email protected] wrote:
    > >>>> I want to know how a gsm mobile gets connected to its network for the
    > >>>> first time when it powered up for the first time given there are six
    > >>>> other gsm operators working. Can anyone help me out?
    > >>> The SIM card contains unique information identifying the specific
    > >>> operator
    > >>> which the phone uses to connect to that operators towers.

    > >
    > > I'd tell you to do your own homework but with the state of Australian
    > > universities these days no doubt you'll just plagiarise it from somewhere
    > > else. And others here may be interested.
    > >
    > > GSM 03.22, 04.08 and 05.02 are the best places to start. What it all boils
    > > down to is that the SIM keeps a 'cache' of the last known location area and
    > > allowed BCCH (Broadcast Control CHannel) list to speed up the PLMN search.
    > > The SIM also has a stored preferred and forbidden PLMN list of network codes
    > > to try. For example, if your SIM is Optus, chances are you'll see 505-02 in
    > > the preferred list (at the top) and 505-01, 505-03 in the forbidden list.
    > > With a smartcard reader you can also inspect the contents of the EFBCCH file
    > > to see what ARFCN channel numbers (frequencies) your network uses.
    > >
    > > Basically, when your phone is turned on, all of these cached parameters are
    > > used in some way to optimize the search for the home network. If this
    > > network can't be found, then the phone tries other networks until it
    > > successfully is able to IMSI-attach ("login") to one of them. This is how
    > > roaming works.
    > >
    > > As for which channels the mobile uses for 'connecting' to the GSM network
    > > (which is not really the correct term, as at most a location update is
    > > performed and then the mobile returns to idle mode) - there are several
    > > used. Strictly speaking, FCCH, SCH, BCCH, RACH, AGCH, SACCH, SDCCH are all
    > > technically involved. However, the two main channels of interest are the
    > > BCCH where all sorts of information about the network is constantly
    > > broadcast over and over again (allowing mobiles to decide which cells to
    > > camp on, whose network it is, etc, etc) - this is how the MS identifies a
    > > candidate cell. Then, when it wishes to IMSI-attach/location update, it will
    > > do this over the SDCCH (Standalone Dedicated Control CHannel), which is used
    > > for most non-voice/data connections (mobility functions, SMS, setting up a
    > > voice call, etc).
    > >

    >
    > I'm curious as well on this topic. So there's a specific
    > frequency/channel that is shared between all mobile providers around the
    > world in which they continually broadcast their network details?
    >


    Not quite. Each base station (well cell really, since a base station
    has multiple cells usually) has a dedicated timeslot on a fixed (i.e.
    non hopping) frequency which constantly broadcasts parameters about the
    network and that particular cell, over and over.

    Thus the mobile has to scan the bands constantly looking for other
    cells to use even if it has found a cell, or to find an initial cell.

    This means searching all channels of the MSes supported bands (900,
    1800, 1900, etc).

    As mentioned before however some of the broadcast (known as BCCH)
    information contains hints about channels and bands to search for this
    network, to speed up search. And the network may have policies on what
    frequencies can carry a BCCH, to further speed up search (or for other
    reasons). For example, Optus in Australia (at least a while back)
    generally used every other physical channel number in their 900
    spectrum (i.e. 41, 43, ..., 79, 81).

    > I've always been curious as to how you can take your GSM phone to a
    > different country, with different networks running of different
    > frequencies (well, deviations from ~900Mhz say), and still pick one of
    > them up.


    Again, normally the MS will keep trying until a network accepts its
    IMSI-attach request.




  7. #7
    FreakyAye
    Guest

    Re: GSM Booting sequence


    thanks for taht info, where can we read more?


    --
    FreakyAye



  8. #8
    FreakyAye
    Guest

    Re: GSM Booting sequence


    thanks for taht info, where can we read more?


    --
    FreakyAye



  9. #9
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    "FreakyAye" <[email protected]> wrote in message
    news:[email protected]...
    >
    > thanks for taht info, where can we read more?
    >
    >
    > --
    > FreakyAye


    "GSM 03.22, 04.08 and 05.02 are the best places to start."

    More generally start with the 02 series documents and work up, as you get
    higher it generally gets more complex and increases the "depth" of
    information.

    03 is a general overview of the system
    04 is protocol & procedures details
    05 is radio layer stuff
    06 is codecs etc

    And you get the idea =)





  10. #10
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    "FreakyAye" <[email protected]> wrote in message
    news:[email protected]...
    >
    > thanks for taht info, where can we read more?
    >
    >
    > --
    > FreakyAye


    "GSM 03.22, 04.08 and 05.02 are the best places to start."

    More generally start with the 02 series documents and work up, as you get
    higher it generally gets more complex and increases the "depth" of
    information.

    03 is a general overview of the system
    04 is protocol & procedures details
    05 is radio layer stuff
    06 is codecs etc

    And you get the idea =)





  11. #11
    Kralizec Craig
    Guest

    Re: GSM Booting sequence

    [email protected] writes:

    >I want to know how a gsm mobile gets connected to its network for the
    >first time when it powered up for the first time given there are six
    >other gsm operators working. Can anyone help me out?


    There are only three GSM operators - Telstra, Optus and Vodafone. All the
    other companies re-sell access to one of those core networks.

    Craig.

    --
    SUN RIPENED KERNELS - Surplus Sun Microsystems Equipment, Parts + Accessories
    Location: Sydney, Australia - Phone: 02-9520-2547 - Fax: 02-9520-2557
    Web: http://www.sunrk.com.au - Ebay: http://stores.ebay.com.au/id=19975645
    Forums: http://www.sunshack.org/phpBB2/portal.php - Mobile: 04-2163-0547



  12. #12
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    "Kralizec Craig" <[email protected]> wrote in message
    news:[email protected]...
    > [email protected] writes:
    >
    >>I want to know how a gsm mobile gets connected to its network for the
    >>first time when it powered up for the first time given there are six
    >>other gsm operators working. Can anyone help me out?

    >
    > There are only three GSM operators - Telstra, Optus and Vodafone. All the
    > other companies re-sell access to one of those core networks.
    >
    > Craig.
    >


    He may have just been illustrating a point of how does an MS locate the
    correct network when there are numerous networks.





  13. #13
    Jeremy Quirke
    Guest

    Re: GSM Booting sequence


    "Kralizec Craig" <[email protected]> wrote in message
    news:[email protected]...
    > [email protected] writes:
    >
    >>I want to know how a gsm mobile gets connected to its network for the
    >>first time when it powered up for the first time given there are six
    >>other gsm operators working. Can anyone help me out?

    >
    > There are only three GSM operators - Telstra, Optus and Vodafone. All the
    > other companies re-sell access to one of those core networks.
    >
    > Craig.
    >


    He may have just been illustrating a point of how does an MS locate the
    correct network when there are numerous networks.





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