Free SMS

This could be interesting to anyone sending texts (SMS): In Ireland, I guess every operator has a so called webaccess which allows you to send up to a certain number of texts for free. Worldwide. That’s kinda handy because sending a SMS via normal GSM mode easily costs you 10ct. A data connection, however, should be much cheaper  (around 4ct. with O2 Ireland, not even 1ct with Simyo in Germany). You only need credentials to log into their website, so no SIM card is (directly) needed.

Because using the web sucks you want to have a nice and clean interface which you can program and extend yourself. Luckily, there are at least two projects, helping you to send SMS comfortably.

One for your PC is o2sms which is really handy. It’s a Perl script and easily useable:

mkdir -p ~/svn/ ~/bin/
svn co
cat > ~/bin/o2sms <<EOF

pushd ~/svn/o2sms/trunk/o2sms3/lib/
../bin/o2sms $@

You have to have ~/bin/ in your path of course. I put the following in my /etc/profile:

if [ -d $HOME/bin ]; then

If you don’t have  a PC at hand, you will find Cabbage useful. It’s a J2ME application for you mobile phone and it’s quite easy to use.

You might even find an (semi) open wireless network using the J2ME app which calculates WEP Keys of Eircom routers, so that you don’t even have to spend the money on the data connection. The algorithm is describere here and you can find a Perl or Python, as well as a C++ implementation here.

On O2, you can send free SMS via normal GSM, so it would be a pity if you had to use the Webtexts. As I discovered that sending SMS via a serial connection is easy, I started to write PySMS. It’s still work in progress, but it actually parses your o2sms configuration file so that you can use send_sms instead of o2sms to send your SMS. To get it working right you might want to enter your phones Bluetooth address in /etc/bluetooth/rfcomm.conf. Mine reads:

rfcomm2 {
  bind yes;
  device 00:FO:OB:AR:BA:ZZ;
  channel   2;
  comment "Mah Mobile";

Dunno exactly how to determine the channel, but I guess sdptool browse should show “Dial-Up Networking” as service name for the channel.

I’d really like to have a wrapper around send_sms and o2sms which decides for me whether it sends the SMS via GSM, Web or both. But my main problem, beside the lack of time, is that I can’t snoop on stdin to pass it to a second program afterwards. Since I don’t really know if stdin must be read, I can’t read it myself and just send it twice. Also, subprocess.Popen is not particucarly happy accepting anything else than stdin or a string. So if you have a solution to this problem, please show up 🙂

The next step is to write a simple webinterface against this o2sms library and have free SMS for everyone 🙂

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Creative Commons Attribution-ShareAlike 3.0 Unported
This work by Muelli is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported.