Hi,

is there any chance to open a GPRS data connection and use standard SMS capabilities at the same time and over the same GSM modem? Can SMSTools manage this some way?

I've read something about "gsm mux daemon" but I don't know much about it...

Any suggestion?

Thanks in advance,
Andrea

SMSTools works only with a dedicated interface. Some "gsm mux daemon" probably can provide this kind of interface at the same time when a GPRS connection is active, but I'm not experienced with those kind of daemons and cannot suggest anything.

If you have much of SMS messages and these are important, you of course should consider to get a real modem for SMS usage. I however assume that you do not have much SMS traffic and probably messages are not very time-critical, right?

How about this: Using a cron, create a script which does the following:
- Check if a GPRS connection is active.
- If it's active, shut it down.
- Start the smsd using init.d/sms3 script.
- Wait for example two minutes (or check the smsd.log).
- Stop the smsd using init.d/sms3 script.
- After smsd is stopped, connect the GPRS back if it was active when started.

This script could run for example once per hour. If there are messages to send, these are sent and incoming messages are read. It is safe to stop smsd using init.d/sms3 script, because this script will wait until already started jobs are done. With a few messages, one minute of running may be enough. From the smsd.log it can be seen how much handling of couple of messages will take time.

This script could also check the /var/spool/sms/outgoing folder: if there are some messages to send, smsd is started to send them and receive messages which probably are available. In this case an external file is needed to store last running time, and cron could run this script every few minutes.

Just an idea, but might be useable without additional daemons. What do you think?

Yes, I was thinking of an application where SMS are of secondary importance and they are not time-critical at all, while the server should be always connected to internet through GPRS (LAN not available).

Generally speaking you are right, it would be ok to close the GPRS connection for a while when a SMS message has to be sent or periodically to check for incoming messages. This is the easy and ready solution.

Technically speaking it would be 'nice' anyway to have both concurrently active, as this is possible with GPRS (when I am surfing the web with my mobile I still can receive/send SMS messages and voice call without interrupting the GPRS connection - also, GSM 07.10 should provide a way to multiplex services over the same serial channel).

I think I'll spend some more time investigating on the mux issue and let you know if anything interesting/useful comes out.

Andrea

I agree that multiplexing would be much more elegant way to work.

At least this project http://developer.berlios.de/projects/gsmmux/ does the job. "The protocol operates between a mobile station and a terminal equipment and allows a number of simultaneous sessions over a normal serial asynchronous interface. This permits, for example, sending of SMS from the terminal equipment while a data connection is in progress."

I however cannot test it right now as I do not have multiplexing mode -enabled device available for testing purposes.

It would be great if you publish any interesting information and/or results you find.

By the way, what is the device you are using? And OS?

The gsmmux project is actually the one i was looking at.
I hope I'll be able to recompile and test it in a week or so.

The device I am using is GR64 based, and it is 07.10 compliant.
My OS is Ubuntu Server 6.06 LTS.

I'll keep you posted as soon as I (hopefully) have some news.

Andrea

I have made some tests with gsmmud daemon with good results.

Downloaded and recompiled alpha-3 version from http://developer.berlios.de/projects/gsmmux/ without problems in Ubuntu 6.06. Just one minor issue, the makefile provided has a small bug but if you download it from the SVN trunk it's been fixed.

Started the daemon with the command:

sudo ./gsmMuxd -p /dev/ttyS0 -d -s /dev/mux /dev/ptya0 /dev/ptya1 /dev/ptya2

Now I have three virtual serial ports (/dev/mux0, /dev/mux1, /dev/mux2) where I can send AT commands to the modem.

Everything seems to work properly with a Wavecom GR64 based modem (I had problems with Telit GM864 but not tested a lot). I have opened a CSD data call in mux0 and sent/received SMS at the same time in mux1 without problems.

The mux seems promising and should be the right solution to use SMS Tools and GPRS connection at the same time.

I did not have the time to test the mux with SMSTools, but it should be just a matter of changing the setup and I do not expect problems. Also, I do not know anything about reliability of the mux daemon. The authors say that it is far from complete, so probably some testing/debugging is needed before using it in a production server.

Thank's for your testing and information.

I changed the title of this topic, so later other users might find this information little bit more easily.