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[ts-7000] Re: gsm1: GPRS and SMS at the same time

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Subject: [ts-7000] Re: gsm1: GPRS and SMS at the same time
From: "Doug" <>
Date: Mon, 10 Jan 2011 19:33:38 -0000

Hi Simon,

I don't have experience with using the GSM1 with SMS, so I don't know how that 
part will work with what I'm about to describe, but I do have more info about 
how to solve the issue of only having one serial port to use to communicate 
with the modem.

It turns out that most GSM modems (including the Wavecom Q64) support the 
AT+CMUX command. It starts up a more complicated protocol that creates virtual 
command channels to the modem, all over a single serial port. You can use one 
command channel for PPP while still talking to the modem with AT commands on 
the other channels. I use it to monitor signal strength and the connected 
wireless network name while the PPP session is still active.

The protocol is pretty complicated, but there are projects out there to make 
use of it. I believe there are efforts to create a kernel driver for CMUX in 
2.6 (not sure on this, though!) but I'm still using the 2.4 kernel. There is an 
open source user space program called gsmMuxd that implements it and creates 
virtual ports you can use. It's not as efficient as a kernel driver would be, 
but it works great in my experience:

http://developer.berlios.de/projects/gsmmux/

Again, I have no idea how this works with SMS -- I'm not sure if the PPP 
connection will like it or not. It might be worth taking a look to see how it 
behaves.

Hope this helps,
Doug

--- In  Simon Leung <> wrote:
>
> Hi all,
> 
> The wavecom modem is a class B device, which means:
> 
> "Can be connected to GPRS service and GSM service (voice, SMS), but 
> using only one or the other at a given time. During GSM service (voice 
> call or SMS), GPRS service is suspended, and then resumed automatically 
> after the GSM service (voice call or SMS) has concluded. Most GPRS 
> mobile devices are Class B."
> 
> But from a programming point of view, there is only one device: 
> /dev/ttyS2. I'm using wvdial for GPRS. Once GPRS is connected, opening 
> /dev/ttyS2 would fail. I can of course kill wvdial each time I need to 
> send SMS but 1. it's ugly, 2. it sounds like for class B device this is 
> not necessary.
> 
> Anybody how this works?
> 
> Thanks
>




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