Question about AT commands and how they are issued through the kernel

Sean McNeil sean at
Fri Dec 12 04:01:17 CET 2008

Hi Jeff,

The GSM modem in the OM phone is connected through a serial interface 
and looks just like any other tty device. You communicate with it by 
opening up /dev/s3c2410_serial0 (on the Freerunner).

Jeff Bickford wrote:
> Hello.  I am working on an independent study research project at my 
> school with the openmoko phone and for the first step we are trying to 
> do something like place a phone call using a kernel module.  I have 
> been trying to figure out the basic flowchart of how a phone call is 
> made and where the kernel comes into play.  I am using the 2008.9 
> distribution on the Freerunner.  I know that the Qtopia stack is used 
> to manage phone calls.  My confusion comes in when thinking about how 
> Qtopia talks to the devices.  At somepoint the software has to talk to 
> the kernel and use the device driver for the gsm modem.  Am I correct 
> in thinking that a call is made by sending some command to the device 
> driver?  I have read how a phone call is made in Qtopia and in the 
> last step an AT command is sent to the gsm device.  My question is 
> where are these AT commands sent through the kernel?  In the end we 
> are trying to send these AT commands to the gsm modem by loading a 
> kernel module.  If anyone can help or can even tell me if this is 
> possible or not it would be greatly appreciated.  Thank you. 

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