Are we legally allowed to change the interface of the Comedian webvoicemail application to incorperate the company’s logo etc, as long as we keep the Asterisk copywrite text intact at the bottom of the page?
Asterisk and its bundled applications (including Comedian Mail) are distributed under the GNU GPL license, version 2. The full text is available here: fsf.org/licensing/licenses/gpl.txt or in the file ‘copying’ included with the asterisk distribution file.
In short, the GPL is designed to be free as in freedom (not free as in no cost). Under the GPL, you are allowed to distribute, modify, change, edit, recompile, or do pretty much whatever you want to the software. There is however one catch- you must provide the same freedoms to your users in the form of source code and licensing, which means all derivative works must also be GPL licensed.
So to answer your question, you are allowed to modify the Comedian Mail interface, logo, prompts, etc. You may even be allowed to remove the Asterisk copyright text (not sure on that one).
ONCE you do such a thing (modify asterisk in any way),
IF you distribute your modifications to other users, either by selling PBX systems, making it available for download, selling software based on it;
THEN your modifications MUST ALSO BE GPL LICENSED AND INCLUDE THEIR SOURCE CODE.
So if you are going to modify the system for your company and use it internally, then you can do whatever you want. But as soon as you make the software available to others (the software itself, not just the services it provides) you must also give them the source code if they ask for it, and your modifications must be gpl also.
Does that answer your Q?
Yes this makes sense. Thank you for your informative answer.
I have one more question, more on the GPL than Comedian.
My company is planning to move from general small/meduim business networking to VOIP phone systems, so I will be “selling” asterisk/comedian a lot, however, I do not want the customer editing thier phonesystem themselves for several reasons, most importatly of which is I cannot be held responsible for problems that their own staff may have caused.
Is not allowing them to make changes to the system theirselves violating the GPL?
if you distribute modified asterisk, you must include the source code to the modification. You can do this by including the source code on the server you sell them if you want. Modifying the source code and changing their configuration are two very different things
You are not allowed to prohibit them from any of the freedoms guaranteed by the GPL (access to source code, ability to create derivative products, ability to distribute or change your modifications)
You are however free to write your service contract however you want to. You can prohibit them from changing the config files, you can prohibit them from recompiling asterisk, hell if you dont want them to mess with stuff, don’t give them the root login. All of this is not covered by the GPL, because it has nothing to do with creating, modifying or distributing GPL’d software. While Asterisk itself is GPL, your work on their system is not. You can’t easily protect the .conf files you write with copyright, but you can easily write a service contract which voids itself if they start screwing with stuff.