Developer question "use of terms.."

Hi @all,

One of my customers want me to install an and change the FreePBX.
They asked to change the look and feel. Replacing logos e.g. and
also to change some parts of the logic. They like to have their corporate design
on it.
I think there is no problem using the GPL, if i put a comment in each page like
"original page from FreePBX changed by …"

But what about the Trademarks on the bottom in each page?
I really don’t know what here is recommended ?

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