Integrated Services Digital Network (ISDN); Circuit-Mode 64 kbit/s 8 kHz Structured Bearer Service Category Usable for 3@1 kHz Audio Information Transfer Service Description
"This standard defines the stage one of the circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3@1 kHz audio information transfer for the pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators. Stage one is an overall service description from the user's point of view (see CCITT Recommendation I.130 [1])@ but does not deal with the details of the human interface itself. This standard defines the interworking requirements of private ISDNs with the public ISDN. In addition this standard specifies the base functionality where the service is provided to the user via a private ISDN. This standard does not specify the additional requirements where the service is provided to the user via a telecommunications network that is not an ISDN but does include interworking requirements of other networks with the public ISDN. Charging principles are outside the scope of this standard. The values of the general attributes are outside the scope of this standard. The circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3@1 kHz audio information transfer corresponds to the service which is currently offered in the Public Switched Telephone Network (PSTN). This bearer service category provides for the transfer of speech and of 3@1 kHz bandwidth audio information such as voice band data via modems@ facsimile groups 1@ 2 and 3 information. The digital signal at the coincident S and T reference point (see CCITT Recommendation I.411 [2]) conforms to CCITT Recommendation G. 711 [3] (A-law). The circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3@1 kHz audio information transfer is intended to support speech and 3@1 kHz bandwidth audio information transfer between reference points. Each of these reference points can be either an S or coincident S and T reference points. NOTE: Network operators can also provide information transfer with the same attributes where the reference point is T. This standard is applicable to the stage two and stage three standards for the ISDN circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3@1 kHz audio information transfer. The terms ""stage two"" and ""stage three"" are also defined in CCITT Recommendation I.130 [1]. Where the text indicates the status of a requirement (i.e. as strict command or prohibition@ as authorisation leaving freedom@ or as a capability or possibility)@ this shall be reflected in the text of the relevant stage two and stage three standards. Furthermore@ conformance to this standard is met by conforming to the stage three standards with the field of application appropriate to the equipment being implemented. Therefore no method of testing is provided for this standard."