Source : Free On-Line Dictionary of Computing

DS3
     
         The third {DS level}, a {framing
        specification} for digital signals in the North American
        digital transmission hierarchy.  A DS3 signal has a
        transmission rate of 44.736 Megabits per second.
     
        DS3 is used, for example, on {T3} synchronous {Integrated
        Services Digital Network} lines.
     
        (1995-01-12)