I am working with that same guy right now but via text messages. I have been stringing him along for three days really messing with him. I will send a dozen texts at a time asking for model numbers, attic, crawl space access, speaker sizes, the house address, cable TV provider etc. I figure the longer I can keep him occupied the less chance has to scam somebody else. It's actually fun to f*@k with him. I got him to send me a drivers license and his CC info. I said I can do the job and accept his terms. He asked what type of CC machine I have and I said I don't have one, I have my CC company handle all the transactions. He asked when can I process the payment and I said not till next Tuesday as I only process on Tuesdays. That made him mad.
I will start calling him at all hours (after *67 as to not reveal my number) just to piss him of even more. When I'm all done the last thing I will do is block his number.

I highly recommend doing this, it really makes for a good laugh.