1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU%.%2!,G0G02%#/-%.$!4)/.3G0G0/.G0G04%,%0(/.%37)4#().G0G0!.$G0G03).!,).3).!,).G0G0).G0G04(%G0G0).4%2.!4)/.!,G0G0-!.5!,3%26)#%3).!,G0G02%#%)6%23G0G0- the maximum duration of 1200 ms has been chosen so as to perm
2、it the partial use of 500/20-Hz signal-receiver equipment.Note 1 - The characteristics of signal receivers of the types used for automatic or semi-automatic workingcould possibly also be used to provide signals and supplementary facilities for operators if the Administrationsconcerned consider that
3、the operational advantages to be obtained justify the equipment modifications involved at theinternational exchanges.Note 2 - The time quoted in this Recommendation for the signal length and the signal recognition timeswould also be appropriate for out-band signalling systems using discontinuous signals for a manual service.
