I have 2 years implementation experiences of asterisk and FreePBX, and knowledge of VoIP and NGN, also doing some projects of PHP. And I always take asterisk as the best IP PBX system all over the world. Now I am getting extremely interested with FreePBX and its related programs for easy to use and colorful applications. So I want to some custom applications based upon web interface. But I just find it’s confusing when I read FreePBX source codes because the comments are always not enough. Can anybody give me some clues, tips or everything concerning designs, theories, structures, etc, such web sites, docs.