From OpenWetWareThe Call extension expects a wiki page and optional parameters for that page as an argument.
Example 1: [[Special:Call/My Template,parm1=value1]]
Example 2: [[Special:Call/Talk:My Discussion,parm1=value1]]
Example 3: [[Special:Call/:My Page,parm1=value1,parm2=value2]]
Example 4 (Browser URL): http://mydomain/mywiki/index.php?Special:Call/:My Page,parm1=value1
The Call extension will call the given page and pass the parameters.
You will see the contents of the called page and its title but its 'type' will be that of a special page,
i.e. such a page cannot be edited.
The contents you see may vary depending on the value of the parameters you passed.
The Call extension is useful to build interactive applications with MediaWiki.
For an example see the DPL GUI ..
In case of problems you can try Special:Call/DebuG