scope:

This ETS is related to Private Branch Networks (PBNs) with a digital access to the Integrated Services Digital Network (ISDN)/Public Switched Telephone Network (PSTN) with a fully 4-wire call path between the Network Connection Point (NCP) and an International Switching Centre (ISC). It applies to call paths carrying 3,1 kHz voice telephony between the NCP and the terminal in the PBN that sets up or answers the call. If a call, before or after it is first answered, is diverted or extended within the PBN, by means of a user-controlled feature, the extended call path is outside the scope of this ETS.

This ETS does not contain a compliance test specification. A compliance test at each NCP for each possible call path within the network would require a prohibitive amount of testing for all networks except the smallest. Furthermore, private networks are subject to frequent changes. Where a compliance statement is provided, it shall be supported by computations and transmission performance data for the apparatus involved (e.g. showing compliance with relevant ETSs).

The limits quoted in this ETS should ensure satisfactory echo and loudness performance.

This ETS does not apply to configurations where a part of the transmission path between the terminal and the public network contains a segment that incorporates mobile systems or cordless telephones.