GPRS with a Cingular SIM card

Discussion in 'Linux Networking' started by Graham Ashton, Jun 21, 2005.

  1. Hi. I've recently purchased a Cingular SIM card that I'm trying to use
    to make a GPRS connection from Linux.

    I've inserted the SIM into a Sierra Wireless AirCard 750 [1]. It's not

    Before I go into detail, I should mention that the config files I'm
    using work perfectly with an AT&T SIM card when plugged into the same
    AirCard, using the same version of the AirCard firmware (there are
    different versions for different providers, though the same version of
    the firmware should work for both AT&T and Cingular SIMs).

    Consequently I doubt there is anything fundamentally wrong with the way
    I'm trying to use GPRS, and that it's more likely something that I
    don't know about how to use a Cingular SIM with GPRS. The obvious
    question is whether or not the SIM is enabled for GPRS, but it was
    purchased from a Cingular shop last Thursday and was only setup with a
    $40 per month data plan.

    Is there anything else you need to do? Do I need to specify a username
    and password for example? The manual configuration guide on the
    Cingular site [2] implies that there isn't.

    Anyway, on to my diganostics.

    My chatscript looks like this:

    '' AT
    OK AT+CGDCONT=1,"IP","\T"
    OK ATD*99***1#
    CONNECT ''

    When I cut and paste the key lines from the chat script into a terminal
    connected to the wireless modem I get the following output. It all
    looks fine to me, right up until part way through the initial hand
    shake from the remote PPP server, when it says "NO CARRIER" and the
    connection drops.

    Welcome to minicom 2.1

    OPTIONS: History Buffer, F-key Macros, Search History Buffer, I18n
    Compiled on Aug 13 2004, 08:34:08.

    Press CTRL-A Z for help on special keys

    AT S7=45 S0=0 L1 V1 X4 &c1 E1 Q0
    +CSQ: 15,0

    ~ÿ}#.!}!}!} }<}!}$}&@}#}$.#}%}&_..Ç}"}&} } } }
    }'}"}(}"e9~~~~ÿ}#.!}!}"} }<}!}$}~


    Note that the AT+CSQ command is reporting the signal strength, a number
    that can vary between 0 and 31; 15 is plenty.

    What could cause the "NO CARRIER" message to appear even though data is
    being transmitted? There is a 20 second pause between the last
    character of the negotiation sent by the server and the "NO CARRIER"
    message appearing.

    I've also recorded the logs from an unsuccessful attempt to connect
    with PPP and the chatscript. I uploaded them to pastebin:

    This chatscript works every time with an AT&T SIM card.

    Does anybody have any ideas? I'm getting really stuck for possibilities
    to explore.


    Graham Ashton, Jun 21, 2005
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  2. Try chaning the above to *99# instead. I'm unable to recall as to what
    ***1 after 99 points to, but it simply is a settings slot/CID I think.
    The *99# will automagically select the defaut and, or active GPRS
    settings from the SIM.


    Dr Balwinder S Dheeman, Jun 21, 2005
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