V.90
V.pcm

    An ITU-T standard modem serial line
   protocol allowing download speeds of up to 56 kbps with
   upload speeds of 33.6 kbps.  V.90 modems are designed for
   connections that are digital at one end and have only one
   digital-to-analogue conversion.

   As of 1998-02-06 the V.90 standard, formerly called V.pcm, has
   been given final approval by ITU-T.  On 1998-10-27 the ITU-T
   announced that approval of the V.90 standard was completed.
   Interoperability testing is complete or in progress for
   several modem manufacturers.  The V.90 standard reconciles two
   competing standards, X2 and K56flex.

   The ITU-T has initiated the approval process for a new
   all-digital version of the protocol, to be known as V.91.

   <ITU Press Release 98-04>.
   and <NP-3>.

   (1999-01-25)