Question 7/I - Telex service
(revised and continuation of Question 7/I, 1985-1988)

Considering

(a) that the telex service is the only text communication subscriber
service available throughout the world;

(b) that it is important to safeguard the Quality of Service as
perceived
by the large customer base of the telex service, particularly in
interworking environments;

(c) that new applications and new facilities for the telex service have
emerged as a result of studies over the previous study periods;

(d) that further development of applications and facilities for the
telex
service is desirable,

a continuation is required of the study of all aspects concerning the
definition and operation of the telex service. Specific points for study
in
these areas are:

1. possible restructuring of all existing Recommendations dealing with
the international telex service, new facilities of the telex service and
interworking of other services with the telex service;

2. identify the necessary operational and service aspects of access to
and from telex to other services and/or networks.

The following aspects should be particularly studied:

-interworking between the telex service and the Videotex service for
direct access from the telex side, using a one-stage or a two-stage
selection procedure on the basis of existing Recommendations;

-interworking between the telex service and the Videotex service using
store-and-forward principles for the telex access on the basis of
Recommendation F.72.

3. consider the possibility of introducing higher speeds and different
code structure into telex network and terminal equipment without
degrading the current quality of the existing telex service;

4. further study of facilities such as store-and-forward;

5. consideration of store-and-retrieve facilities for special
applications;

6. security of the service (e.g. assurance of delivery);

7. study the aspect of telex connections in prolonged idle conditions;

8. the influence of the network on the quality of the telex service;

9. what steps should be taken to allow the use of non-latin character
set in the international telex service?

Note 1 - Collaboration is necessary with Study Groups VII and VIII for
the interworking scenario, with Study Group IX on technical aspects
and with Study Group III on charging and accounting aspects.

Note 2 - At the IXth CCITT Plenary Assembly, two administrations
expressed reservations on some paragraphs of new Recommendation
F.73, the reasons for which are listed in the annex to this Question.

ANNEX

(to Question 7/I)

Reservations to Recommendation F.73

The reservations concern the following paragraphs:

3.1.2.6

Reason for the reservation: data networks do not all necessarily
transmit the address of the called (or calling) data terminal (see X.25
(1988), Appendix 4).

3.2.3

Reason for the reservation: same as for  3.1.2.6.

3.2.6

Reason for the reservation: the possibility of the telex terminal
answerback being carried by the data transmission network must be
studied in greater detail before this idea can be accepted in principle.
4.2.3

Reason for the reservation: the solution indicated (call release in both
directions) is too different from the solution normally adopted in the
telex service. The conversational mode is no longer possible. This point
should be studied at a later stage.