Data call (aka CSD) with QtExtended

Ed Kapitein ed at
Sun Mar 22 12:23:21 CET 2009

Tuan TRINH wrote:
> Yes, my GSM carrier support both data/fax and I also did register it.
> Thought we need to interact with modem directly to make data calls,
> unfortunatety Qt has not much info on how to to this.
> Ed, do you have any experience on using it?
> On Fri, Mar 20, 2009 at 11:37 PM, Mike Montour <mail at
> <mailto:mail at>> wrote:
>     Ed Kapitein wrote:
>     > I am also looking for a way to make data calls, do you know of
>     any other
>     > method of making a data call with the FR?
>     > ( direct AT commands to the modem etc)[...]
>     > All pointers are welcome!
>     First you need to make sure that your GSM carrier supports CSD (mine
>     doesn't AFAIK) and that it is activated on your account.
>     In the past people have mentioned that the Calypso performs
>     similarly to
>     an "Enfora Enabler" modem and there is some web-accessible
>     documentation
>     for that. The "AT+CBST" (select bearer service type) command seems
>     to be
>     involved.
>     There's probably some overlap between the CSD commands and the
>     ones used
>     for GPRS so I would also look at
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Hi Tuan/TAT(?),

On om2008.12 i was able to make a data call using simple AT commands.
I need to login to my provider with username/password, and that  will be
mailed to me next week.
So the data call works, i am not yet able to start ppp over it, due to
the missing username/password, but i think it will work.

I use gsm0710muxd, so i first request a channel with:
identvar=$(date +%s)
MODEM=$(dbus-send --system --print-reply --type=method_call
--dest=org.pyneo.muxer /org/pyneo/Muxer
org.freesmartphone.GSM.MUX.AllocChannel string:$identvar | grep string |
awk -F '"' '{ print $2 }')
echo "${MODEM}"

And then start minicom  (mikey term might work just as well)
and issue the AT commands.

atdt <your dial-in number here>

You might want to experience with
AT+CBST=0,0,1 to get auto baud rate

There is a bug with gsm0710muxd, (#2223 ), so if you experience packet
loss, you can use the /dev/ttySAC0 directly.
First kill all applications using the gsm modem ( in my case qpe ) and
check with lsof if /dev/ttySAC0 is not used by anything else.
then make the data call.

The data call is charged from your airtime account, so be carefull with
the costs! i need to figure out some callback/callfrward scheme, to cut
the costs....

Kind regards,


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