catflap.org Online Dictionary Query

  Integrated Services Digital Network
       
           (ISDN) A set of communications standards
          allowing a single wire or optical fibre to carry voice,
          digital network services and video.  ISDN is intended to
          eventually replace the plain old telephone system.
       
          ISDN was first published as one of the 1984 ITU-T Red Book
          recommendations.  The 1988 Blue Book recommendations added
          many new features.  ISDN uses mostly existing Public Switched
          Telephone Network (PSTN) switches and wiring, upgraded so
          that the basic "call" is a 64 kilobits per second, all-digital
          end-to-end channel.  Packet and frame modes are also
          provided in some places.
       
          There are different kinds of ISDN connection of varying
          bandwidth (see DS level):
       
          	DS0  =    1 channel  PCM at      64 kbps
           T1  or DS1  =   24 channels PCM at   1.54  Mbps
           T1C or DS1C =   48 channels PCM at   3.15  Mbps
           T2  or DS2  =   96 channels PCM at   6.31  Mbps
           T3  or DS3  =  672 channels PCM at  44.736 Mbps
           T4  or DS4  = 4032 channels PCM at 274.1   Mbps
       
          Each channel here is equivalent to one voice channel.  DS0 is
          the lowest level of the circuit.  T1C, T2 and T4 are rarely
          used, except maybe for T2 over microwave links.  For some
          reason 64 kbps is never called "T0".
       
          A Basic Rate Interface (BRI) is two 64K "bearer" channels
          and a single "delta" channel ("2B+D").  A Primary Rate
          Interface (PRI) in North America and Japan consists of 24
          channels, usually 23 B + 1 D channel with the same physical
          interface as T1.  Elsewhere the PRI usually has 30 B + 1 D
          channel and an E1 interface.
       
          A Terminal Adaptor (TA) can be used to connect ISDN channels
          to existing interfaces such as EIA-232 and V.35.
       
          Different services may be requested by specifying different
          values in the "Bearer Capability" field in the call setup
          message.  One ISDN service is "telephony" (i.e. voice), which
          can be provided using less than the full 64 kbps bandwidth (64
          kbps would provide for 8192 eight-bit samples per second) but
          will require the same special processing or bit diddling as
          ordinary PSTN calls.  Data calls have a Bearer Capability of
          "64 kbps unrestricted".
       
          ISDN is offered by local telephone companies, but most readily
          in Australia, France, Japan and Singapore, with the UK
          somewhat behind and availability in the USA rather spotty.
       
          (In March 1994) ISDN deployment in Germany is quite
          impressive, although (or perhaps, because) they use a
          specifically German signalling specification, called 1.TR.6.
          The French Numeris also uses a non-standard protocol (called
          VN4; the 4th version), but the popularity of ISDN in France
          is probably lower than in Germany, given the ludicrous
          pricing.  There is also a specifically-Belgian V1 experimental
          system.  The whole of Europe is now phasing in Euro-ISDN.
       
          See also Frame Relay, Network Termination, SAPI.
       
          FAQ
          ftp://src.doc.ic.ac.uk/usenet/news-info/comp.dcom.isdn/)" rel="nofollow">(ftp://src.doc.ic.ac.uk/usenet/news-info/comp.dcom.isdn/).
       
          Usenet newsgroup: news:comp.dcom.isdn.
       
          (1998-03-29)
       
       

  integrated services digital network
     n.
     The integration of data and voice communications services that are
  transported over digital facilities of various physical types.

  integrated services digital network
     n.
     The integration of data and voice communications services that are
  transported over digital facilities of various physical types.

  integrated services digital network
     n.
     The integration of data and voice communications services that are
  transported over digital facilities of various physical types.

  integrated services digital network
     n.
     The integration of data and voice communications services that are
  transported over digital facilities of various physical types.

  Integrated Services Digital Network /ˈɪntɪɡɹˌeɪtɪd sˈɜːvɪsɪz dˈɪdʒɪtəl nˈɛtwɜːk/
  ISDN 

  integrated services digital network /ˈɪntɪɡɹˌeɪtɪd sˈɜːvɪsɪz dˈɪdʒɪtəl nˈɛtwɜːk/ 
  digitaalinen monipalveluverkko
  integrated services digital network

  integrated services digital network /ˈɪntɪɡɹˌeɪtɪd sˈɜːvɪsɪz dˈɪdʒɪtəl nˈɛtwɜːk/
  digitalna mreža integriranih usluga