| 摘要 |
The specific case considered here is that of frequency subdivision at nominally 2700 Hz, 2800 Hz and 2950 Hz of a 4-wire circuit into a main band (which can be used for telephony, data, phototelegraphy or facsimile transmission) and a secondary band, above the main band, reserved for Vfrequency-modulation (FM) telegraphy.
The solution described in this Recommendation is recommended when the equipments are supplied by the Administration for use on leased circuits and when the derived voice channel is used on the public switched telephone network. It should be pointed out that, in accordance with the Recommendation cited in [1], Administrations are not obliged to accept any responsibility for the end-to-end quality of transmissions over connected circuits which comprise a private leased circuit network.
It is understood that any other system may be used on a leased circuit, provided the conditions concerning levels given in § 5 are observed; in this case, Administrations can give no guarantee concerning the quality of circuits, to the users of a leased circuit. |
PDF(76M) 
您当前的位置：
ITU-T ITU电信标准