Question 27/I - Providing customer satisfaction and efficiency when
using world-wide telecommunications
(revision and continuation of Question 7/II,
1985-1988)

Considering

(a) that customer difficulties and errors in using the international
automatic telephone network can produce economic losses resulting
from customer confusion and dissatisfaction;

(b) that it is necessary to test the effectiveness of some of the
existing
Recommendations and to keep them up to date;

(c) that some new voice (and non-voice) services with international
implications may give rise to customer problems, interfering with the
success of those services;

(d) that the ISDN may lead to changes in the traditional procedures for
using the PSTN or its equivalent in the ISDN;

(e) that interworking between networks may present difficulties to
customers;

(f) that many national ISDN trials are in progress or will be conducted
during the study period;

and furthermore, considering

(g) that human factors and the concept of usability of human-system
interfaces is of prime importance for users, administrations and
manufacturers;

(h) that usability measures would aid in the avoidance of user
difficulties by improving the design of services;

(i) that usability is composed of several independently measured
parameters, the most important of which are: error rates, performance
time, learnability and subjective assessment;

(j) that in other areas of human factors (e.g., human-computer
interaction) studies have been carried out leading to some usability
measures;

the following issues should be addressed:

i) detect and remedy significant customer difficulties in the PSTN;

ii) anticipate and avoid significant customer difficulties arising from
the
introduction of the ISDN (e.g., through data gathered in ISDN trials);

iii) recommend methods for providing assistance to users during
communications sessions;

iv) maintain and improve existing Recommendations dealing with
customer performance (e.g., E.120, E.122, E.123, E.124, E.125, E.126,
E.127, E.128);

v) make or amend Recommendations on existing and new services to
reduce difficulties with services operating internationally;

and furthermore,

vi) How can such methodologies be developed and validated as reliable
measures?

vii) To what extent should such a methodology be applied to the
evaluation of user interfaces to telecommunications services available
via the ISDN?

viii) What measurement methodology of usability is the most
appropriate for standardization?