Just called the number back and was connected to their automated "opt out" service. Says to allow 24 to 72 hours for the number to be removed., You have to confirm the number that called and your number to be added to their do not call list.
NEVER NEVER NEVER CALL BACK AND REGISTER WITH THEIR AUTOMATED OPT OUT SERVICE! All you have done now is let them know this is a "live" number (that is, a number with a person on the other end). Now they will keep calling or sell your number to someone else. Always let a number unknown to you go to the answering machine or voicemail!
If you are on the do not call registry, to to the website www.donotcall.gov and register a complaint! See the buttons on the left side of the page. FILL IT OUT. The more people complain, the more likely this number will be shut down or fined.