caller claims to represent a "national debt consolidation company" that'll shave 45% off my credit card debt at a 0.0% rate. caller id shows up as "Redwood, City CA"

I missed a call on my cell phone and they didn't leave a message.  When I called back, the automated "the number you are calling has been disconnected or is no longer in service".  Interesting.....  I know the prefix as being Redwood City because I used to live there, otherwise I would not have called back.