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INTERNATIONAL TELECOMMUNICATION UNION )45 4 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU 6BIS $!4! #/--5.)#!4)/. /6%2 4(% 4%,%0(/.% .%47/2+ ")43 0%2 3%#/.$ -/$%34!.$!2$):%$ &/2 53% ). 4(% '%.%2!, 37)4#(%$ 4%,%0(/.% .%47/2+ )45 4 Recommendation 6 BIS (Extract from the "LUE "OOK) NOTES 1 ITU-T Recommendation V.26bis was published in Fascicle VIII.1 of the Blue Book. This file is an extract from the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the contents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below). 2 In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. © ITU 1988, 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation V.26 bis Fascicle VIII.1 - Rec. V.26 2400/1200 BITS PER SECOND MODEM STANDARDIZED FOR USE IN THE GENERAL SWITCHED TELEPHONE NETWORK (Geneva, 1972; amended at Geneva, 1976 and 1980, Malaga-Torremolinos, 1984) The CCITT, considering (a) that there is a demand for data transmission at 2400 bit/s over the general switched telephone network; (b) that a majority of connections over the general switched telephone network within some countries are capable of carrying data at 2400 bit/s; (c) that a much lower proportion of international connections in the general switched telephone service are capable of carrying data at 2400 bit/s; unanimously declares the view (1) that transmission at 2400 bit/s should be allowed on the general switched telephone network. Reliable transmission cannot be guaranteed on every connection or routing and tests should be made between the most probable terminal points before a service is provided. The CCITT expects that developments during the next few years in modern technology will bring about modems of more advanced design enabling reliable transmission to be given on a much higher proportion of connections. Note - The provisions of this Recommendation are to be regarded as provisional in order to provide service where it is urgently required and between locations where it is expected that a reasonably satisfactory service can be given. The study of improved methods of transmission at 2400 bits/s or above over the general switched telephone network will be urgently continued with the aim of recommending a method of transmission which will enable a more reliable service to be given over a high proportion of the connections encountered in normal service. (2) that the characteristics of the modems for this service shall provisionally be the following: 1 Principal characteristics a) Use of a data signalling rate of 2400 bit/s with carrier frequency, modulation and coding, accordin