Missed the call. When I called back I got a recording telling me that if I'm receiving unwanted sex calls to please leave a message with my 'dialed number' and it will be removed within 48 hours. The recording begins by stating a company name that I couldn't understand - it was too garbled. Maybe someone else will have better luck?
Like many others I add these bogus numbers to an appropriately labeled contact name in my phone directory (the rules say I have to watch my language so I can't post the actual name I use :)) and I set the ringtone to silent. I haven't found reporting these numbers to the government to stop the calls - so it just makes sense to take care of it myself. I appreciate a site like this and the people that contribute info so my life can be a little more spam-free. Thanks everyone!