Question 8/II - Service quality of networks, including operational
performance
and service measurements (PSTN/ISDN)
(Continuation of Question 22/II amended, studied during the
1985-1988 study period)

Introduction

This Question has two parts:

The first part (considerata (a) to (e) and items 1 and 2 of the
Question)
serves as a continuation of studies on operational performance of
networks including service measurements. It recognizes the previous
development of Recommendations on operational guidance, connection
establishment and connection retention. The main thrust of this
Question will focus on connection quality; the use of supplementary
information contained is common channel signalling systems to improve
service quality of networks, and the migration towards the ISDN.

The second part (considerata (l) to (q) and items 1 and 2 of the
Question) addresses the general framework of future studies on
service quality requirements and operational performance of networks.

In this study period studies will focus on PSTN and ISDN.

Considering

(a) that the main parameters describing the service quality of networks
are given in Recommendation E.420;

(b) that the CCITT has adopted Recommendations E.426 on connection
establishment and E.428 on connection retention;

(c) that common channel signalling systems (C6 and C7) are being
introduced into the international network and the enhanced capabilities
of these systems could provide additional information to enable a
detailed analysis of call failures;

(d) that delays in call establishment, e.g., post-dialling delay, and in
particular variation in the delay, significantly influences service
quality;

(e) that techniques based on speech envelopes may be applicable for
the automatic measurement of connection quality;

(f) that billing is adversely affected by the absence of answer signals
on answered calls or by the presence of false answer signals;

(g) that service quality measurements and improvement programmes
are integrally related to network management and network
maintenance activities;

(h) that significant input is obtained from the Quality of Service
Development Group (QSDG);

(i) the necessity to identify the contact points within each
administration for service quality improvements;

(j) that the Telecommunications Management Network (TMN) can be
used to transport measurements including text call and observation
data;

(k) that in view of the increasing complexity of networks and services,
the timely publicizing of number plan changes is an important means of
maintaining service quality at the time of such changes;

(l) a framework is necessary to harmonize future studies on service
quality of networks;

(m) Recommendation I.350 on general principles of Quality of Service
and network performance in ISDN has been prepared;

(n) Recommendations X.134 - X.137 and X.140 adopting these principles
for data services are already available;

(o) relevant studies will continue especially in Study Groups VII, XII
and
XVIII;

(p) the principles, results and future works mentioned should be taken
into account in studies relevant to service quality of networks;

(q) guidelines are necessary now to handle Quality of Service and
network performance problems in Study Groups A and B,

1. What modifications should be made to the E.420-Series of
Recommendations and to other relevant Recommendations to reflect
the need to ensure the operational performance and service quality of
networks?

2. What benefits can be gained by improving the service quality of
networks?

3. What general framework of further studies on the operational
performance and service quality of networks should be applied?

Note 1 - Reference should be made to the study of Q.9/II - Network
management and Q.10/II - Traffic measurement requirements on
telecommunication networks (including the ISDN) because the outcome
of the study will most likely comprise the inclusion of more parameter
measurements in Recommendation E.425. Close liaison will be required
with other Study Groups.

Note 2 - Close liaison is needed with Study Groups VII, XII and XVIII.