scope:

This ETS specifies the usage of all protocols and supplementary services up to and including layer 4 for telematic terminals in the ISDN. The scope of this ETS is limited to demand circuit-switched calls using the 64 kbit/s unrestricted digital information bearer capability and the DTE/DTE case of the Network Layer peer entities in B-channel connection. This ETS is based on other ETSs, International Standards or CCITT Recommendations and, where necessary, it adds new or other requirements as application rules.

The telematic services considered are:

a) teletex;

b) facsimile group 4; and

c) ISDN syntax-based Videotex.

The ETS is applicable to terminals using either basic access or primary rate access to the ISDN. Basic access and primary rate access refer to different ETSs for layer 1.

NOTE: In the context of this ETS, and in the case of Videotex, a terminal is either a real terminal equipment, a Videotex service centre, a Videotex access point or a Videotex host.

Conformance testing to verify to which extent a terminal conforms with this ETS is to be specified in a separate ETS which will cover both the Protocol Implementation Conformance Statement (PICS) proformas and the Abstract Test Suites (ATS).

Interworking capabilities and limitations with implementations following similar Standards such as Functional Standards are described in informative annexes.