Voice-Grade Special Access Network Voiceband Data Transmission
|Publication Date:||1 May 1994|
This standard provides transmission performance objectives for point-to-point voiceband data (VBD), voice-grade special access (VGSA) services covering the bi-directional path between an exchange carrier's (EC) end-user network interface (NI) and an interexchange carrier's (IC) point of termination (POT) (see figure 1). Throughout the document, the term, VGSA, implies point-to-point VGSA. Moreover, throughout the document, for consistency with previous standards, the designation, exchange carrier (EC), is used, but is intended to include all providers of special access services.
Transmission performance objectives for multipoint services require further study and therefore are not covered. Within this document, the term, IC, refers to interexchange carriers and any other connecting entities. Both originating (access) and terminating (egress) special access services are covered, and are referred to in this standard simply as special exchange access. VGSA is an element of voice-grade special services similar to that provided in what has historically been referred to as private line, leased line, or private network services.
The transmission performance objectives specified in this standard are based on end-user needs and applications, characteristics of voiceband data modems, and capabilities of evolving telecommunications networks. A discussion of end-user application needs, and the relationship of these needs to voiceband channel transmission performance, can be found in annex A. The objectives are considered to be reasonable criteria for circuit acceptance and restoral1). Actual in-service performance will depend on the initial values and variance of parameters, not the objectives alone. Therefore, the objectives may not be met on all circuits or on any particular circuit at all times. In such cases, the carriers and end-users should work cooperatively to achieve a level of performance within transmission maintenance limits specified by the EC. This standard does not preclude the possibility of separate negotiations between carriers to implement other levels of service.
This standard is intended to be used by the telecommunications industry to cooperatively provide service quality appropriate for end-user application needs. The use of this standard helps to ensure the ICs about the quality of the VGSA services and enable ECs to implement and maintain VBD-VGSA network arrangements. This standard is a product of a number of considerations. Among them are customer service needs, network architectures, the technical capabilities of transmission and equipment systems, as well as operational and economic concerns. See annex B, Bibliography, for examples.
1) Parameters measured for circuit acceptance and restoral will depend on the network provider's service offerings and may not include all the parameters specified in this standard.