Caller ID says "WCNH".  They leave a message.  Their software is too stupid to wait for the beep, so the start of the message is cut off.  I hear, "... monitoring your credit card accounts for the last 6 months.  Congratulations!  On your excellent payment history you now qualify for a zero percent interest rates on all your credit card accounts.  If you've completed this process or not interested, press 3 now.  Otherwise, press 1 now to speak to our qualification department and complete the process.  The qualification process can be completed in a few minutes. <pause>  Goodbye."

This is the notorious credit card rate reduction SCAM.  You pay them a ton.  They ask your credit cards to lower your rate.  You can do this as effectively yourself for free.

I call back during the day (using *67 to block my number).  I hear, "the number you have reached 229 0947 in area code 603 is not in service.  Please, check the number and dial again."  So this appears to be a disconnected number.  Likely the caller has spoofed the number.

I googled this number, and it did correspond to WCNH.  WCNH sold to NPR in August 2014.  So there is no way they are calling anyone.