Short for “Digium Asterisk Hardware Device Interface”
DAHDI is the new name for ‘Zaptel‘ as of May 19th 2008.
The post at http://blogs.digium.com/2008/05/19/zaptel-project-being-renamed-to-dahdi/ details the reason for the change. Asterisk 1.4 releases later than 1.4.21, and all releases of Asterisk 1.6, will automatically use DAHDI in preference to Zaptel, even if Zaptel is still installed on the system.
Details should be available at http://www.asterisk.org/zaptel-to-dahdi
svn co http://svn.digium.com/svn/dahdi/linux/trunk dahdi-kernel
svn co http://svn.digium.com/svn/dahdi/tools/trunk dahdi-tools
Or a shortcut (if you just want to get it working, not if you want to work on it). It pulls the above two through svn:externals .
Conversion from Zaptel
Note that unlike zaptel.conf, you have to explicitly set the echo canceller for each channel.
There are a number of other configuration files under /etc/dahdi .