The Free On-line Dictionary of Computing (19 January 2023):

RFC 1568

    An RFC defining the Simple Network
   Paging Protocol (SNPP) which is designed to support
   Internet access to paging services such as those based on
   the Telocator Alphanumeric Protocol.  See also RFC 1861.

   (rfc:1568).

   (1996-06-24)