[asterisk-dev] A legal question

[mbodbg at gmx.net]

Hello all,

nearly all modules written for asterisk are distributed under the terms of
the GPL.

...

* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.

...

In practise that means that everybody can use and distribute that code for
private or commercial usage. Code Changes must be made accessible for the
public.  

In some modules I can find an additional licence notice:

* A license has been granted to Digium (via disclaimer) for the use of
* this code.

What's behind that License Notice? Which additional rights are granted to
Digium by that License Notice? 

Best Regards

Markus