GSM Modems for SMS sending

By dose | November 14, 2018
Under: Uncategorized

We have a bunch of Falcom A2 modems here for automatic sending of SMS-messages to customers.
These modems have a weird firmware bug i nversion 01.93.07 that causes the modem to stop working when the +CMGS message counter overflows after sending 255 messages. Back in 2010, I asked Faclom support if there was a firmware update for the modems and they just lied to me and said, there was only one Firmware version, they are not supporting it anyway and I should buy a new modem.
So I found out that I could reset the modem with

and the counter gets reset.

However during the years, the GSM modems still showed some bugs and became a bit unreliable over time, which caused quite some annoyance.
So we checked the marked of GSM modems and found some OSTENT Wavecom Q2303A/2C/2C2 based GSM modems. They seem to be sold by Chinese manufacturers. Se we bought a serial and an USB-variant of the modem.
It turned out that they come with no support, are really old rebranded Wavecom-hardware (which was overtaken by Sierrawireless company, which doesn’t offer any support for old wavecom Hardware) and no firmware updates are available.
This was especially annoying, as these modems (both RS-232 and USB-variant) seem to have a major defect:
Sending SMS works great, but receiving SMS only works once and then it never receives SMS messages again, whatever you try to do. So these modems are rubbish, don’t buy them!

So I was back with my Faclom A2 modems. Turned out that there were Firmware updates for these modems indeed. Thankfully the wonderful Wayback machine archived them from the old manufacturer’s site!
Unfortunately, the other interesting documentation is gone forever, but I preserved what I was able to get (including most recent firmware) here. The a2_flash.exe is a WinZip selfextracting archive containing the most recent firmware.
When applying the most recent firmware to the A2, the SMS counter bug vanished and modems are currently working stable (crossing fingers that it stays that way).
Now updating these modems seems very complicated, as the manual just says that you need to short some PIN, you probably don’t even have access to. But it turned out, that it works this way:
1) Start the FlashBurner.exe, select COM port
2) Unplug the modem from power.
3) Hit the “Start download” button in the FlashBurner application
4) Hold down the RESET button of the modem (in the pinhole) while plugging in the power cord
5) Release the RESET button
The FlashUpdater should start downloading the firmware. If it doesn’t work, you can try a few times, it works after a few attempts.

So hopefully, this hint helps those who are still having these old Falcom A2 modems.

I set up another site with SMS functionality. As these was no modem available and these OSTENT are trash, we bought an old used TC65 Java Terminal, which seems to have been attached to a printer for communication with manufacturer. These Java modem Terminals seem to be able to run some embedded software on them and then communicate over serial line with the host.
However we wanted to use it as a normal modem executing AT-commands. So I did some research and found out that there is a way to disable the embedded application. For this, you need the SDK of the modem which contains an application wtk\bin\autostart_off.exe
Start the application, tell it to disable autostart and the nquickly unplug and replug the modem. After a few attempts, it should work and modem can be used in normal operation mode.
As the SDK doesn’t seem to be easy to find, I mirrored a copy of it here.

So far for my adventures with GSM modems. Hopefully, the information here is useful for some ppl.

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