The threads "Enochian Evocation is Not Based on English" and "Is Enochian Based on a Gnostic Text" discuss the likely origins of the calls. To continue along this theme, I've posted on Sorcerer.net an brief argument discussing some circumstantial and stylistic evidence that Kelly might have plagiarized the Calls. Here's the post:
http://sorcerer.net/did-kelly-plagiarize-the-calls/
And here are the two posts on this forum that discuss the issues surrounding the Call's origins:
http://studioarcanis.com/viewtopic.php?f=18&t=6743
http://studioarcanis.com/viewtopic.php?f=18&t=6803
I'm very interested in what the various magi on this forum might have to add (or subtract) from the idea.