Audio Ads/Pay Per Play

Hello,
I was searching for different types of ads and my attention was caught by pay per play ads but they don’t seem to be very popular so I don’t want to waste my time with scams. I decided to ask first – do you know reliable ones that really pay? I found these for now:
http://www.sellingppp.com/
http://audiovoiceads.com
Please post your comments,
Thank you!

See original post by blank_jack