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				==Phrack Inc.==
		     Volume One, Issue Two, Phile #6 of 9
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		Toward Universal Information Services Via ISDN
		~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~ ~~~ ~~~~
				 by Taran King

		From PROTO newsletter of AT&T Bell Laboratories
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	 Phase one, the Present.
	 ~~~~~ ~~~~ ~~~ ~~~~~~~~
  The local network of today, although still largely voice-oriented, is
 already on the path to Universal Information Services.  Lightguide fiber is
 dramatically expanding the capacity of local networks, helping to lower the
 costs and increase the demand for high-band width, Information Age services.
 And public networks are increasingly digital and geared for data and special
 services.  For example:

  o The AT&T Network Systems 5ESS (TM <riiiight>) switch, designed by Bell
 Laboratories, can serve as the hub of a local deployment of remote modules at
 locations up to 100 miles from a host central office.

  o The Integrated Special Services Network (ISSN) is a channel network that
 provides special services, customer control options and digital private lines
 rearrangeable under software control.	The ISSN incorporates digital carrier
 terminating equipment such as the D4 Channel Bank, D5 Digital Terminal System
 and Digital Access and Cross-connect System (DACS).

  o The New Centrex is bringing greater levels of customer control, improved
 services and a broad range of data capabilities to the business customer.

  Today's public networks consist of multiple or overlay networks.  The public
 switched network, or circuit network, mainly for voice, is the base network.
 Two kinds of overlay networks provide special services.  Channel networks
 carry private lines leased by large customers and transmit much of today's
 data and image traffic; they also handle traffic for network operations
 support.  Packet networks carry data communications, while packet switching
 is used internally to public networks for common channel signaling to set up,
 route and take down calls, or to give customers information.  "Overlay
 networks help telecommunications companies efficiently meet growing demand
 for digital transmission and special services," says Stan Johnston, Market
 Planning Manager, Network Systems Evolution, in AT&T Network Systems.	"Their
 integration into a single network, however, would be still more effective."

	 Phase two, the Integrated Services Digital Network (ISDN).
	 ~~~~~ ~~~~ ~~~ ~~~~~~~~~~ ~~~~~~~~ ~~~~~~~ ~~~~~~~ ~~~~~~~
  The ISDN is a concept to which AT&T is committed - and it's the foundation
 for Universal Information Services.  The central idea of ISDN, as AT&T
 Network Systems sees it, is to provide an individual user a link to the local
 central office of generous band-width - a digital subscriber line that can
 carry 144,000 bits per second (sure beats 2400 baud!).  The band-width is
 subdivided into two 64,000-bit channels, which may carry voice or data or
 both, and one 16,000-bit channel for packetized signaling information or data
 transport.  Such a link provides convenient "integrated" network access by
 accommodating voice, data and signaling over a single line.  The ISDN will
 make it easier for a customer to get varied services from public and private
 networks.  More bandwidth for big customers will be available through another
 ISDN access standard, the extended digital subscriber line, which provides
 1.5 billion bits per second as 24 channels of 64,000 bits each.  In 1986, new
 software from Bell Labs will enable the 5ESS switch to accommodate ISDN-sized
 144,000-bit channels that standardize and simplify subscribers' use of local
 networks.  AT&T is committed to future products that will also be
 ISDN-compatible.  Other vendors, too, some of whom already plan to build
 premises, terminal, and other equipment to ISDN standards, will make ISDN a
 cooperative effort.  By providing integrated digital access to networks, ISDN
 will make important progress toward the goal of Universal Information
 Services.  But overlay networks will continue to divvy up the transport job.
 And messages needing less than 144,000 bits per second will not fill their
 allotted bandwidth, leaving capacity underutilized.

	 Phase three, Universal Information Services.
	 ~~~~~ ~~~~~~ ~~~~~~~~~ ~~~~~~~~~~~ ~~~~~~~~~
  Rooted in the fertile ground of 5ESS switches, ISDN equipment and
 technologies such as wideband packet transport, Universal Information
 Services will bear fruit during the 1990s.  From a single kind of network
 will hang services as different as apples, oranges and pears.	Just as
 network access was integrated in ISDN, transport functions will increasingly
 be integrated by powerful new network equipment evolved from equipment
 developed for the ISDN.  Where customers once got standard-sized ISDN
 channels, they'll get big bandwidth for large jobs, little bandwitdh for
 small jobs.