V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DS0
       Digital Signal level 0 (ISDN, T1), "DS-0"


The Free On-line Dictionary of Computing (30 December 2018):

DS0

    The zeroth DS level, having a transmission
   rate of 64,000 bits per second (64 kb/s), intended to carry
   one voice channel (a phone call).

   (2001-03-18)