Section 17-101. Acknowledgment or new promise must be in writing

An
  acknowledgment or promise contained in a writing signed by the party  to
  be charged thereby is the only competent evidence of a new or continuing
  contract  whereby  to  take  an  action  out  of  the  operation  of the
  provisions of limitations of time for commencing actions under the civil
  practice law and rules other than an action for  the  recovery  of  real
  property.  This  section  does  not  alter  the  effect  of a payment of
  principal or interest.