To download, make and install the script and required modules:
cpan -i WWW::SMS::IE::iesms
For Debian (and Ubuntu) heads, there is a apt repository at apt.mackers.com with the required packages. To install o2sms, as root:
echo "deb http://apt.mackers.com/ unstable contrib" >> /etc/apt/sources.list
apt-get update
apt-get install o2sms
This package will be synchronous with the CPAN package; apt-get update will always get the latest version.
To verify the package signature: curl http://www.mackers.com/about/gnupg.key.asc | apt-key add -