scope:

This standard defines the stage one of the circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for speech 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 speech information transfer is intended to support speech information transfer between reference points. Each of these reference points can be either an S or coincident S and T reference points (see CCITT Recommendation I.411 [2]).

NOTE: Network operators can also provide information transfer with the same attributes where the reference point is T.

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 network may use processing techniques appropriate for speech such as analogue transmission, echo cancellation and low bit rate encoding. Hence, bit integrity is not assured. This bearer service category is not intended to support modem derived voice band data.