THE COMPUTER BOARD AND THE RESEARCH COUNCILS


 NETWORK EXECUTIVE


 JANET USER NOTE 4


 The Packet Switchstream Tariff


                                                            Issued by
                                             W. Jenkins and S.A. Wood
 Issue 2                                             8 September 1987


 ____________________________________________________________________

 1.  Introduction
 ----------------

 This document gives the charging  rates  for  making  calls  to  the
 Packet SwitchStream  (PSS) and the International Packet SwitchStream
 (IPSS).  The charges are calculated on the basis of  both  time  and
 the amount  of  information sent, in Kilosegments.  One segment is a
 packet of information that can hold up to 64 bytes of data.  Thus if
 you were to send 65 bytes of data you would use 2 segments.

 2.  Tariff Rates
 ----------------

          PSS and IPSS Charges for 1987 (Revised 15th July)
          -------------------------------------------------

 Destination             Duration charge        Volume charge
 -----------             ---------------        -------------

 U.K. Full rate          0.0167p /  2 secs       0.030p / 1 segment
 U.K. Discount rate      0.0111p /  2 secs       0.020p / 1 segment
 Europe                  1.5   p / 30 secs       0.9  p / 5 segments
 N. America              3.75  p / 30 secs       2.25 p / 5 segments
 Rest of world           4.5   p / 30 secs       2.7  p / 5 segments

 A PSS/IPSS accounting unit is one segment (up to 64  characters)  or
 that duration of call which would cost the same.

 This duration is 3.6 seconds (Volume charge / Duration  charge)  for
 all destinations this year.

      Destination         Cost(pence)/Unit
      -----------         ----------------

      U.K. Full rate           0.030
      U.K. Disc rate           0.020
      Europe                   0.180
      N. America               0.450
      Rest of world            0.540

 The cost of a call is (Duration(seconds)/3.6 + segments)  multiplied
 by the cost per unit.  This does not include V.A.T.

 British Telecom are  introducing  a  minimum  charge  for  all  call
 attempts except  those  which  fail  because of their network.  This
 will be the cost of transmitting 5 segments of data for  30  seconds
 for all  IPSS  calls  and  the  cost of 50 segments plus appropriate
 duration charge for U.K.  calls.

 All U.K.  calls between 1800 and 0800 plus  Sundays,  Christmas  and
 New Years day are charged at the discount rate.

 PLEASE NOTE THAT SATURDAY CHARGES ARE NO LONGER DISCOUNTED