Callback leads to "the number you have called has been temporarily disconnected".  A clear sign of scammers.  Also, there are a number of indications that even this message is not being provided by a phone company, but is a spoofed message being delivered by the scammer's number, (which itself has a spoofed caller ID).

ITs2014 if you don't know who's calling don't pick it up. Don't call the number back ...do you know Mary stewart.? Why waste your time if you call back they have caller id and will coninue to call you back.let sleeping dogs lie

Caller ID said, Mary Stewart.  I answered and got a recorded spiel about credit card rates.

Got the call a few minutes ago; no message left, Caller ID said Not Available with this number shown preceded by "11-".  I would agree with above posting "it is 2014, do not answer the phone..." if caller is not known.  If important they will leave a message for you to call back; certainly do not call back any number if such scam message is left.  Being in business it is hard for us to adjust but rather lose a client than face financial disaster.   Additionally with "11" preceding the number, appears to indicate the scammers are now having to identify that they are calling from overseas.  If so, then suggest never answering the phone as per recent news articles about overseas calls locking up your phone line for a while and your next phone bill will have an exorbitant charge racking up $10, 20 or more dollars a minute!  BEWARE!    

SCAM CALL  DO NOT ANSWER!!

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