This Document applies to transmission within private networks and the interconnection of private networks with oter - mainly public - networks. It should be considered as a tutorial and illustration for the planning of private networks with respect to the voice transmission quality of narrowband 3.1 kHz real time telephony via handsets. networks designed according to this document will also provide sufficiently high speech quality for the transmission of announcements and stored speech.

This document does not address the transmission of non-voice signals such as Fax- and Modem transmission and wholly digital data transmission.

The main application of this document is to medium and large private networks consisting of several interconnected MLTS. The terms "Corporate Network" or "Enterprise Network" are sometimes used to describe a large private network; in some countries this term is used in a legal sense for a group of interconnected private networks. From the point of view of transmission planning, there is no difference between a large private network and several smaller interconnected networks. Therefore only the term "Private Network" will be used in this document.

The document addresses only scenarios where a "private network" functions as a terminating network (one to which terminal equipment is connected). Scenarios wherein a private network provides transit connections between other networks are outside the scope of this document, as are the following issues:

• who owns and runs the network

• who is responsible for transmission quality

• to whom services are provided

Notwithstanding these limitations in the scope, the principles and the information described in this document may be applied to other end-to-end connections.

For the purposes of this guide, there are no restrictions on the private network with respect to size, configuration, hierarchy, technology used, and network components. The transmission media may be cable, fiber or radio.

The discussion in this document addresses primarily the use of digital interfaces between the private and the public network (nearly universal in Europe) but also allows for analog private-to-public network connections. The signal transmission within the private network may be analog or digital.

The prevalence of digital signal transmission media and digital signal handling in switching equipment impacts the relative importance of various transmission parameters to be considered in planning. For the benefit of simplification, parameters with only minor impairments in a digital environment, such as the frequency shape of cables, circuit noise, crosstalk, variations of loss with level or time etc., are not subect to the planning guidelines in this document. More emphasis is placed on parameters such as echo, return loss, delay, signal processing equipment impairments, and acoustic characteristics of terminals.

This document does not contain transmission requirements for specific network elements such as telephone sets, switching equipment (PBXs) or transmission equipment. It is assumed that the design of such elements conforms to applicable regional standards or regulations.