[mod.telecom] Bar codes, ISDN

johnl@harvard.HARVARD.EDU@ima.UUCP (12/31/86)

Bar codes on the mail:  The postal service has new high-speed sorting
equipment which reads the bar codes and sorts the mail.  They also are
putting in OCR equipment that reads the bottom line of the address and
prints the bar code.  Companies that pre-print the bar code on their
envelopes are likely to get their incoming mail faster, since the P.O.
can skip the OCR step and proceed directly to the sorting.

ISDN:  There was a whole issue of the AT&TTJ (nee BSTJ) on ISDN earlier
this year.  The standard 2B+D interface allows one 16KB supervisory channel
which is always X.25-like data.  This channel is used to exchange messages
to control the other two channels, but you can use it for virtual circuit
data, too.  The other two channels can be used for anything you want, such
as high speed data or voice.  The channels can be assigned to various
services per-call, so at different times you could have two voice calls,
two data calls, or one of each.  The standards for the X.25-like channel
seem to be be pretty well defined, but what they're haggling about now are
some rather fundamental things like how to encode voice into the 64KB
channel, and how to encode the three channels onto a phone line.  There is
also a 23B+D interface for larger systems like PBXes, which would map 23 64KB
channels plus another 64KB supervisory channel onto a T1 trunk, and there's
still wrangling about that, too.  Don't hold your breath.

John Levine, ima!johnl or Levine@YALE.something