All downloadable files are hosted in SourceForge. Please proceed to there in order to download Tellu package.
You may also checkout an SVN repository by
$ svn checkout https://tellu.svn.sourceforge.net/svnroot/tellu tellu
if you want to download a development version of Tellu. Development version usually contains some features and/or fixes that are not yet packed in distribution. It is also possible to explore the source code online from http://tellu.svn.sourceforge.net/viewvc/tellu/trunk.